I suggest waiting about 2 weeks before adding any fish. The plants will have bacteria on them to start the ammonia/nitrite consuming bacteria colony you need, but it takes some time. Add just a few fish at first, less than a half dozen, wait about a week or two, and add a few more, wait a week or two before adding the rest of the fish you want. All of that is contingent on the plants being actively growing, not just sitting in the water slowly rotting.
I'm not sure how much light you have, but I think it is low enough that you won't see really fast growth. If you add Excel to your dosing, that should help the plants quite a bit. And, pushing a few substrate fertilizer tabs under some of the plants would help too.