If you're getting a WHOOSH-BANG, it should not be doing that. Too much powder in the pan may cause it, or too small a touch hole, or poor sparks from the flint. Dribbling powder into the touch hole is more likely to slow ignition than to speed it up. You don't want a fuse. You want a blast of hot gas through the touch hole to the main charge.

I tend to wipe the frizzen and flint after every couple of shots, and after every shot in Summer heat and humidity. But I can go ten or fifteen shots without having to poke the touch hole.

Powder in the pan should be below the bottom of the touch hole, not blocking it. In both of my flinters, a level layer across the entire pan seems to work best, and it doesn't take much. I would call my pans about 1/3 full. You should also consider some black English flints instead of the Agates. Some folks seem to have good luck with Agates, but I'm not one.