I'm not 100% sure about the growth rate of convicts. Oscars however do grow very quickly to have to keep an eye on the situation. 2 inches is a little bit dodgy with a reasonably sized Oscar. Even a 5 inch Oscars has got quite a big mouth and it may well attempt to eat the convict even if he's got no chance of actually swallowing it.
Regarding the pleco, unless your tank is absolutely caked in algae most of the time, you will have to supplement their diet with things like how algae wafers, cucumber, aubergine, things like that.
Also, slow down when you're typing