Make sure you scrub the surface with some
: detergent and water to get rid of any blush. Blush will
: interfere with the drying of the varnish.

According to the epoxy manufacturer's information for West System and System Three epoxies
I have read, the only solvent recommended to remove amine blush is water.

Yes, water IS a solvent. We don't think of it as one since we drink it.

Detergents or other solvents can be a source of surface contaminants which will cause problems with varnish
curing, fish eyes and orange peal.

Most solvents are recycled and contain all sorts of contaminants and who knows what is in that detergent!

Each epoxy is a combination of chemicals and as it cures the surface has a residue of this mix which
may or may not interfere with the curing of the varnish.

I did not know this on my first boat and I applied a varnish which was not compatible with the epoxy I used.
The varnish never fully cured. It gummed up my sandpaper when I tried to sand between coats.
I was a sticky mess I had to remove. I still smell the tacky varnish I didn't remove inside the hull, after 20 years!

A properly cured varnish will sand without clogging 220 sandpaper.

Each epoxy manufacturer will be able to tell you which varnish will work with their epoxy. Contact them. It's worth it!

If you can wait 30 days for the epoxy to fully cure you might not run into problems.

But if you have problems once, you will probably not find the risk worth taking.

I have found the first coat of a compatible varnish on week old epoxy still takes two days to cure.
The following coats cure in one day.

All the best,
Rob