I would start by reducing your list a little bit..... those fish will do great for a while in a 125 but they all get big, and grow fairly quickly and in 18months time you'll find yourself overstocked and battling with water quality...... which is important as some of those fish really will not tolerate poor water quality for long.
So, from your list, I would comment as folows:
Semi-larvatus Butterfly - nice fish, will get very big.
Larvatus Butterfly - very difficult species, best avoided, even by experienced aquarists - maybe choose a nice substitute like the red back (from red sea)
Imperator Angelfish OR Majestic Angelfish - emporer much too big for a 125, ultiamtely.... majestic may eventually outgrow it, but you are talking 3-4yrs down the line.
Flame Angel - nice fish
true perc vs. false perc QTY: ??? - a pair
Blue Hippo Tang - small / medium QTY: - 3 is too many - withing 18-24months these fish should be 6-8" ...... if not they are not being cared for properly..... and they are very active.
So.... I would get the following, in this order:
A pair of tank bred "perc" clowns.
Red backed B'fly
Semilarvatus B'fly
Regal tang (about 3" is ideal)
Flame angel
Majestic angel (small adult - about 3" would be ideal)
You could also look at adding a few smaller fish.... hawkfish, gobies, blennies, grammas, wrasse...... that sort of thing.... just add them before the flame angel ..... shoudl be ok with the majestic though.
I would advise slight caution when introducing the flame angel and majestic.... flames can be quite aggressive, and majestics are everything but..... so a smaller flame (2") and a larger majestic (3"), and not too much time before introductions.
In terms of time inbetween..... it depends on your set up really, more than anything. If you are talking a week or two between introdutions, then you are looking at a fulyl stocked tank in 6-12 weeks, which is MUCH too quick..... your asking for trouble at that rate..... it should be 3-4 weeks for a new tank.
HTH
MAtt
