Stenciling on wood - mistakes were made

Hello all,
I'm a novice and beginner. I'm making a giant 6-foot ruler with which you can measure your kids and mark it instead of using the wardrobe door. Simple plank with markings and numbers, and the kids names.
I got a planed white wood plank (probably pine), stained it with Oak stain, and then drew the cm and inch markers with permanent marker.
I got the stencils of the numbers, stuck them down, and used a sponge dabber to apply acrylic paint. Unfortunately the paint bled under the stencil and feathered into the wood, so I sanded the paint off, re-stained as necessary, and thought about what to do.
I was going to finish the whole thing with polyurethane anyway so I applied one coat of that and let it dry. Then I stuck the stencils down again. I'd read a tip online about applying a thin layer of PVA glue mixed 2:1 with water to seal the stencil to prevent bleeding, so I did that.
Once that was dry, I applied the acrylic paint again using the sponge dabber. Once that was dry, I removed the stencils and was disappointed to see that the paint peeled away with the PVA leaving nothing behind on the wood. I am assuming that the polyurethane prevented the PVA and paint from sticking.
So now I have the ruler with index markings and a coat of polyurethane. What can I do to apply the number stencils? Do I need to sand the polyurethane to make it stick? Any tips about preventing stencil bleed?
Grateful for any help,
Matthew

Lightly sand the surface so the paint can stick better, then wipe off the dust. Don’t use glue this time,use stencil spray or tape to hold it in place.

Masking tape has saved my bacon on projects like that; I just burnish the edges hard before brushing the paint, then peel the tape while it’s still damp. I also started using http://freeprintablestencils.com/ for cleaner numbers because they print true to size, and I can cut them from card so the bleed is way less. A light sanding and a second stain pass usually hides most early mishaps.