I have new ceiling in my bathroom installed by my contractor. I gave him primer/sealer to apply on new drywall ceiling before painting it.

Looks like he cut corner and did not apply primer and directly painted the ceiling with white paint.

I wanted to seal drywall before paint , is it too late now ? Can I still apply this primer/sealer and paint again ?

I am using [this KILZ 2 water-based primer](https://tinyurl.com/5kf66skc).