What I do is double filter all my cycled tanks. When I want to start up a new tank, I take a filter cartridge from a cycled tank and put it into the new tanks filter. Then I put a new one back in place of the one I took from the cycled tank. Best thing to do it place it right into the filter of the new tank and let it run. You'll need fish in the tank though, because that bacteria needs to feed off ammonia and such that fish produce. I am not sure about Glofish, but Danios are very hardy fish and should have no issue with it. I do this with all my tanks.
**You could always do this with Filter Fiber (looks like polyester fill) instead of filters to save some money**
You could double up your filter in one of your cycled tanks now, and in a week or two transfer it to the 20g and then your cycle should be jump started. Just add some new Glofish, so you can quarantine the new fish and cycle at the same time. Then when everything is stable, add your Glofish you have now. A week later, add your neons and quarantine some new neons in the 10g when it's empty. That's what I would do anyways! Don't add fish all at once or you overload the bacteria and the cycle could crash.