Hi Jo, once you have qualified the filter (meaning it has big robust bacterial colonies that could handle a full stocking of the tank) you will no doubt actually stock less (sometimes considerably less) than a full stocking and the size of the bacterial colonies will adjust downward. This is exactly what we want and once we stock fish we want to no longer ever really worry about the feeding of our bacteria, the fish respiration, fish waste, excess fishfood and plant debris will all be providing plenty of ammonia and the bacterial colony sizes with gain and lose according to the bioload (usually just the fish stock, but sometimes some shrimp and snails etc.)
The initial stocking right after a fishless cycle is the *only* time one can do a massive stocking. Forever after that its better to just ease the number of fish upward (assuming the plan allows it) very slowly so that the bacteria have plenty of time to react and increase their numbers without a "mini-spike" (traces of poison re-appearing) occurring. I usually like to just go easy. I might add a "mini-shoal" of 5 neons (as an example of below average size fish) or three of some average sized fish or just two of a larger type. I let them spend a nice long time in my quarantine tank (usually months) and then introduce them to the main tank (usually on the same day as I bring home new fish for the quarantine tank) assuming I'm in a phase of stocking a tank and have multiple batches coming.
~~waterdrop~~