You're pushing it to the limit really, especially with so many glofish. I have limited experience, however in regards to water changes theres no universally correct answers. But personal opinion, I feel like you're overstocked.
The first thing i recommend you do is buy a liquid test kid - API master test kit is probably the most widely used. Test for ammonia, nitrites and nitrates. Ammonia and nitrites should be 0 or else your tank isn't cycled, and you should aim to keep your nitrates at a low level - under 20 is generally accepted.
Monitor your levels over the course of a few weeks, performing water changes when nitrates get to 20 or more. Your nitrates will decrease at the same percentage you do your water changes - eg, if your nitrates are 20 and you do a 25% water change they should decrease to 15 (25% reduction). You will soon know how often your water needs to be changed and how well it works for you - such as performing more frequent, small changes, or less frequent larger changes. Typically with an overstocked tank, water changes are necessary to be performed more often.
Also you should forget any "inches of fish to gallons rules" you've heard of, as they are often a very inaccurate means of determining stocking levels. AqAdvisor.com is a good means of determining stocking levels based on your specific tank and fish