It's kinda like which one came first, the chicken or the egg.
Depends on the look you want, how sharp the checkering is, what kinda blasting media you are using, and what the "feel" you're after.
I checker first, with the mill or checkering files and then do the blasting with ceramic bead and light air pressure.
Take some scrap material and try it several ways. Sometimes the best final product comes after a few mistakes. No, us knifemakers don't make mistakes, we modify existing patterns.
Hope I helped.