if you can get the pH down closer to 7.6 it might help and since you have only just started I wouldn't worry too much about the acid killing the bacteria but you could simply add your ammonia and let the natural cycling takes it's course without bringing the pH down much more. As the system cycles the bacteria will naturally use up the buffering capacity and eventually you may find you have to add top up water to keep your pH up or even add some other form of buffer to keep the pH from dropping too low.
Personally I prefer to use drift wood to reduce the PH it’s a gradual process but no chemicals needed. Best to use a PH down from an aquarium store as it made for fish and yes the temperature makes a difference to the type and growth rate of the bacteria’s. But that said it also takes about 4 to 6 weeks for the bacteria’s to grow.
Hope this helps