Oops, I saw it was 18 and change. One of the purposes of fishless cycling is to have the ability to stock a large % of your fish immediately. A lot of people err on the side of caution, but as long as you are adding peaceful community fish...I don't see any problems. In my 48 gallon I added 9 neons, 7 Red Eye Tetras and 8 Leopard Danio / Glofish mixed school right off the bat. My bio-filter didn't blink an eye and all the fish were more than happy and content.
As long as you cycled at 4ppm, I think it'd be perfectly acceptable to add both the Tetras and Danios at once. I'd wait a week or two keeping an eye on water parameters, add the Corys, wait a week or two then add the Ram or Dwarf Gourami to finish things off. If you planned on adding shrimp at any point (I have Amanos and RCS) they have virtually no bio-load so you can add as many as you want, whenever you want.