I use the 24 oz Ball pickling jars, and clean them weekly. Testing the ammonia it's only starting to be a problem by that time.
I will take a clean jar and add clean water that's up to temperature (i have a tool to spot check water temp). I pour the fish into a net, and then put him/her in the clean jar quickly, so that the whole event is over before the fish knows what's going on. I then rinse the net with warm tap water, take the freshly cleaned jar back and get another dirty jar and repeat the process. Clean the jar from the last fish, fill with fresh water, ect.
I weaned my fry off of aged water at around the 2 month mark and just used fresh mixed & primed water.
I seems rough but they're going to be breeders and show fish, so they have to be strong and resilient. Worked pretty good for me so far.