How long should a fresh entry ramp stay taped off?

You'll probly want to wait at least seven days before anyone is putting a lot of weight on that ramp, and even then it's on the safer side. While it feels rock solid now, concrete continues to gain strength through hydration for a while longer. Most structural integrity is set quickly, but achieving full strength takes weeks. For light foot traffic, a week should be fine, but heavy loads or repeated use before two to three weeks is risky. About backfilling the dirt around the forms, you can probably fill it in now as long as you don't pile any heavy equipment or pressure on the edges. Just fill it up with soil or gravel, maybe dampen it a bit, and tamp it down. Wait til the main slab is fully cured before doing any heavy landscaping around it, though. As for peeling off that plastic from the brick, the trick is to apply a little bit of something sticky or a good quality solvent like rubbing alcohol to the plastic before pulling. That helps it release from the rough surface of the brick without snagging or leaving dried mortar dust behind. If it's a very dry day, you can also spray the brick itself with water right before you peel it back, which often breaks the seal between the sheeting and the material. Remember that the finish and joint work you did are critical for how it looks and how it performs long term. Keep an eye on any hairline cracks once the curing process is completly finished. If you see anything that looks like it might be pulling away from the base or the forms, that's when you'd need to investigate the subsurface. Good job getting the job done, though. It's definatly a huge task to get a concrete job done on your own for the first time.

Agreed on giving it the full week, maybe longer if the weather's been cool. When I did a small pad behind my garage I kept it damp for the first few days by laying a tarp over it and wetting it down each evening, and it seemed to cure slower and harder that way. Cool temps especally slow things down, so if your nights have been chilly I'd lean toward waiting closer to two weeks before the Sunday crowd starts using it.

On the plastic over the brick, when I did the steps at my old place I didn't cover anything and paid for it, so you're alredy ahead. The dried spatter bits that get past the sheeting come off easier if you lay a wet rag over them for ten or fifteen minutes first. Then a plastic putty knife pops them off without scratching the brick face the way a metal blade will. Scrub any ghosting left behind with a stiff nylon brush and plain water. Don't go near muriatic acid unless the water method really fails, it can eat the brick face and leave a bigger mark than the splatter.

On the foot traffic thing, what I'd worry about at a church isn't grandma walking on it, it's somebody rolling a piano or a stack of chairs across on a dolly. Point loads are what scuff a young slab. I'd leave the cones up until the weekend after next and make an announcement, saves you the arguments. For the backfill, I kept mine a couple inches below the slab edge so water drains away instead of sitting against it. Learned that the hard way when my sidewalk heaved one winter. Also plan on sealing it before freeze season hits if you get snow, salt will chew up fresh concrete fast.

Update: tried the wet rag trick on the brick and the spatter came off with a plastic scraper after about fifteen minutes, saved the paint job. Also quoted the dolly point to the committee, cones stay up till after next weekend and I'm announcing it Sunday. Kept the slab damp under a tarp too. Still fuzzy on the backfill though, do I fill that dirt gap now or hold off?