How should I paint accents over oil-based stain?
After staining give a coat of clear finish, sanding it with a fine sandpaper (400G) to remove any raised grain or any dust that may have settled onto the drying finish.  This will give you a good base to add your paint and the sanded surface will give it good adhesion. Steel wool has its purpose, but I would not use it here. That's only my opinion. My experience is the steel wool sheds metal bits everywhere, and may be a deal to clean up completely.

After the recommended dry time for the paint is over, give it your final clear coat.
I know this did not answer your question about how long to wait before the top coat, but depending on what brand of paint you use, makes a difference. Each paint container always list how long it needs to dry before the next coat. Many usually only need 8 hours.

If you do not have that, the safe rule of thumb is, 24 hours if oil over oil, 2 days if water over oil. I don't know what to recommend if oil over water.