Hi Chris, I can't add much else to what the other members have suggested, but the one point that doesn't seem to have been covered is the varnishing of Water Thinnable Oils.
This isn't my first medium, but as a rule of thumb, I would advise that paintings produced with Water Thinnable Oils are still, essentially, Oil Paintings, and as such they should be varnished after about 3 months, to allow the paint to change to its fully dried state.
Perhaps any members who are more Au fait with the system may have more accurate advice, but this is how I would proceed.
Good luck, and very best wishes,
PA & RSC Wigan area