only one problem that i can see: that common pleco is gonna get HUGE, and they're known for uprooting plants. a 20 gallon is way too small for it. i'd exchange or sell it if you can, and get a bristlenose pleco instead.
EDIT: actually, i noticed you only have one cory cat... they're a lot more fun/lively in groups! i'd get at least a couple more of them, maybe instead of a bristlenose. i guess that depends on how much algae you need eaten though (go for the BN if you get a lot of algae).
EDIT EDIT: my bad, didn't see you already were trying to get a bigger home for him. awesome