Depending upon the size of the SCB, and the rating the amount of heat will vary...
I usually fly a Corvette and use a 7A shield bank(i have 2 but turn one off), and i have a button assigned to use it and another for the heat sink(I use a HOTAS). But you could assign them to a fire group if you wanted to- and link them both the heat sink & SCB to one trigger- just remember what fire group they are in.
To prevent overheating (read 140%+ heat) and module damage from the heat generated off the SCB, you will may need to use the heat sink first, then the SCB. As the heat sink lasts about 10 second and the SCB lasts about 7-8 seconds(don't quote me on this) you have a few seconds to use it, before you loose the benefit of the heat sink.
I typically use mine when the second ring of my shields is going down- or if i am about to engage several targets.
Like others have said, there is typically a 2-3 second delay before the ship opens up a can of coke(the sound of the SCB) and you will hear it whine, and increase in pitch as it completes the recharge.
Again, if your shields go down when it is recharging, you will waste the shield bank.
A pro tip is to use the type B module to start with, as you will get an extra charge out it and generate less heat. But you will also get less "shield recharge", but this should more than fill your shield, unless you are using a large class 7A or 8A shield. A side effect is the additional weight, but only you can make that decision.
With the changes that FD made to the shield cell banks, bounty hunters(like me) run 2 shield banks, and 2 sets of heat sinks, so we pick the type A module to get the greatest amount of recharge out of a single shield, as we only have 8 heat sinks. We turn one SCB off, and then once the first one is empty, we turn it off, and the full one on, this takes about 45 secs- so pick your time to use it- NOT in the middle of combat- but you may not have that option.
Additional factors to take into consideration
The FDL has great thermal dissipation, and can use a SCB pretty easily, unless you have been on the trigger for a long time-
PAY ATTENTION TO YOUR HEAT if you are not using a heat sink. Another is the Viper mk4, as it has a lot of internal slots. So don't be afraid to experiment with them to find the right balance for your ship.
There are a lot of variables revolving around your thermal heat signature, such as:
The amount of time on the trigger- more thermal weapons fire, more heat
Boosting, yes this gives your ship a huge amount of heat!
The type of modules you have, specifically the CLASS, as A rated modules have the best heat dissipation, lesser rated ones will result in lesser heat dissipation.
The type of ship you have, like i have stated, some ships have great heat dissipation already.
So to recap.
Buy a cheap type D rated one, preferably the same size as your shield(or larger) - because if you have a smaller one, you loose of "recharge rate, on a sliding scale"... thus the smaller it is when compared to your shield, the less recharge you will get(also less heat).
Assign it to a button(you pick) or a fire group)
Just fly out of the station,
turn off your shields, and boosters - remember the boosters INCREASE the recharge time(aka LONGER to recharge) and let your shields recharge, until the come online.
Then hit the SCB, you`ll hear it pop, then whine as it does its thing.
Now PAY ATTENTION TO THE HEAT GENERATED. The reason for this "test" is for you to understand just how hot your ship will get with out using any weapons.
Next test is to fly away from the station about 12k.
Put full power to weapons, and start using them, until you empty the capacitor(if you can) and turn off your shields- this is a test to see how long it will take to regen in combat. Balance the pips at 3-0-3, and keep firing, and giving yourself heat.
Use the SCB, and note the heat- you should get a LOT of heat- depending on your ship- again note what is happening.
This information tells you two things- if you need a heat sink or not, and how long your BASIC shields take to come online, remember adding shield boosters increases the recharge time, but also the amount of "recharge", as the total amount of shield may be a lot higher vs the basic shield (5x A0 boosters = +100% shield).
Recomdations
Use coriolis to build your ship, and see how much shield recharge you will get off a SCB.
http://coriolis.io/
For example my Corvette has 1333MJ of shield, but the 7A SCB only recharges 1125MJ of shield, where a type 7D SCB only recharges 520MJ of shield, meaning i`d have to use 3 charges off my type D scb to max it out to full, or typically 2 to make it full off 1 ring. But only 1 charge if i used the type A rated SCB module(which i do).
These figures are very important for you as a pilot, knowledge is power!
Understanding the differences between the CLASS and SIZE will help you make a more informed choice when building your ship- and they are totally free on Coriolis, so feel free to mess about with your ship. This is because you will need either
more SCB's (as in run 2 SCB's together) to recharge your shield, or a
BETTER CLASS(more expensive + use more power) of SCB to achieve a full shield.
Remember some ships- specifically the Vulture have very limited power, and as such you will need to carefully balance out your build. Also your ship may have very limited internal compartments- remember this!
Hope this helps... yes its a lot of information, but once you understand WHY it is important to have these figures, it will make a lot more sense.