I have been using Tamiya primer (gray or white) in a rattle can. Warm it slightly, 2 light sprays with at least 24 hours of drying in between coats. I usually do this at least a few days, often a week to allow curing before I use acrylics from my Paasche VL for the colors.

I’m 2-3 years out on several 3-D prints, no problem with paint adehesion.