If you are fishless cycling the tank then it's safe to add the entire tank stocking at once as the beneficial bacteria will be built up enough to handle the bio load of all those fish. It's actually the best practice to do it this way for african cichlids.
I would like to point out that it's not the best idea to stock peacocks along with Mbuna as the mbunas are much more aggressive.
"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations." -Occam's razor