maybe
@Ian Doncaster can answer that with some colonia edge case.
generally factions are inserted with +10 influence points/raw influence/gross/gain/you-name-it --- leading to 9,0909 influence points in a no-traffic/no-input system after expansion, after which influence calculations are applied. so i
think expansions happen pre influence calculation.
therefore invasion should be decided by last ticks completed influence calculations taken into account as it is with retreat going through, or with expansion going pending.
but i have no exampel to back that up, also because an invasion leads to locked influence by invasion conflict, so it's actually hard to tell what have been the influence level "directly before" invasion.
it doesn't bother me much not to know though - if you work to get "that" invasion and not "those others" it should be very unlikely not to invade the system you want to go to if you have managed to set up the systems accordingly after the last tick - assuming you are not sniped or (much more likely) a victim of fate called random traffic.
generally the best way to get "that" expansion and "not those" is to lock all others non-native in range into conflicts during the 3 ticks expansion can happen, which is much easier with all the odyssey assets around these days.