Setting up a tank if you can use tank water and matured filter media couldn't be easier. All you need to do is put about half a tank of tank water in with half a tank of dechlorinated, put some mature gravel and plants in there and put the matured media in the filter. Then you could put about half the fish you want straight away, the other half a week later (after checking parameter to be sure everything is going to plan). Dont do any water changes during this period and for another week. Then do about a 15% water change and from then on do about 10% twice a week forever, vacumming gravel and cleaning filters once a month. Glad you are thinking convicts, they are the most interesting you could put in a tank that size. Personally i think you best choices for that tank would be either 2 pair of kribs if you want breeding, or 1 female convict, 1 rainbow cichlid and maybe 1 male Krib or an Angelfish or possibly a Keyhole. I find bolivian rams a bit uninteresting and other rams hard to keep. You could possibly put a pair of bristlenose plecs and 5 congo tetras in for company.