OK, I am doing 3/4" solid IPE over concrete, with one of the suggested methods (6 mil plastic, 3/4" CDX ply, 15 lb felt paper). However, I did have to flatten the slab first, and to my surprise, I have used 400 lbs of concrete patch material, and I expect I will use another 120 lbs before I am done. Some of the areas required 1/2" or slightly more! Needles to say, it's been a lot of work for a first-timer. My concern now is that there may be a lot of water in that extra concrete. I have never heard of anyone waiting x many days before proceding (except newly poured slabs), so I wanted to check with experts here. Should I wait just a couple of days? A week? Thanks!

You need a Tramex Concrete Moisture Encounter, to check for moisture in the float.

Are you going to fasten down the plywood? Are you going to poke holes in the poly?

Yikes, that Tramex meter is expensive. Does anyone rent those? Can I do the "tape plastic over area" test?

The plywood will be fastened down with concrete screws, and I plan to insert some sealer/adhesive in the holes before putting the screws.