So let me teach you how to figure this out.
What ester are you using, for primo we have E and A, I'll assume E since A would be weird. What test ester are you using? compare the release rates. Assuming you're using Test E or C, those esters release at the same rate as Primo E, so you should probably co-inject because you don't want to have massive peaks and valleys in your blood serum level. There are some graphing tools that can assist you in visualizing ester release rates, like
https://www.steroidplanner.com/ which can be helpful tools when trying to figure out dosing schedule.