A lot of people will use Sanding Sealer in the process of painting or staining their boards. Generally, this will seal the boards slightly to allow for a better finish in the following steps.
Using Sanding Sealer
From TedwNV - This is my personal experience but a lot of people disagree with me on here. Hasn't failed me yet.
1. First coat of sanding sealer.
2. Wait an hour, sand first coat. This should take you about 1min MAX!
3. Apply second coat of sanding sealer.
4. After second coat dries, you can apply your tape if you're painting borders or other logos. I always apply a thin coat of sanding sealer over the edge of the tape.
5. After paint has dried, apply your decals if that's what you're doing.
6. Apply poly.
In your case the way I read it.
1. Stain 2. Sanding sealer (dry) 3. Sanding sealer 4. Decals 5. Poly
So...two coats max on sanding sealer.