it took me between 3-4 weeks round trip to Sagittarius A*, this was pre-passengers, pre-neutron-star scooping and pre-colonia (was a bucket list item at the time). My ASP Explorer also had a jump range of 56LY on a full tank.
things i found out...
1. Getting there was "fun", i made loads of new discoveries, farmed the neutron star fields and had a blast generally.
2. Going back home is the hard part, it's like having a migraine on a Roller coaster, your near the front and sat between wasp nests and a group of school kids, who had bad tuna sandwiches, rotten yogurt and fizzy drinks for lunch. And than finding out the ride never ends and wasps are expert at flying fast... the migraine becomes the least of your worries as you know this ride has at least 3 loop-de-loops.. forwards and backwards!
3. you can be 20,000LY in the middle of no where and if you go into an asteroid field or the rings of planet... pirates will still find you and they will scan you.
4. be prepared! take the biggest A.F.M.U. and more importantly, the biggest Fuel scoop you can.
5. Never, ever... ever, try to repair your FSD in supercruise. it will not be a good experience.
6. there is no novelty shop in Sagittarius A*, it's a fairly boring system to be honest. you'll no doubt see plenty of black holes on the way, and the one in the system is like, just bigger. it's the same feeling when you were a kid and was given a "jawbreaker gobstopper", looks great to begin with but after a while you realise that's actually pain your feeling in your jaws.
7. there is an area on the way which is full of non-scoopables, if your fuel tank drops between 1/3 - 1/2, check the map for scoopables, easiest way i remember them are KGB FOAM, because you know, the K.G.B. probably have the strongest foam currently known.
8. it's worth doing just so you know you've done it, i wouldn't go to Paris without at least seeing the Eiffel Tower, Amsterdam without visiting the coffee-shops/seeing the "culture" something-something or eating sausages in Germany. perhaps thats just me though.
hope that helps, or not, i don't care as i already did it
good luck Commander and fly safe... or Fly dangerous, again i don't care.
Lee