I can't lie, back in the day I ran primo alone as a bridge between cycles. Can't remember how long I was on but really didn't get anything out of it. Nowadays I would have to agree with Tinyshrek and only run test alone.
this^^^^ is true... but the 'back in the day' part is what is the stickler... back in the day, you probably could make pretty decent gains with 'stronger' aas, and now that you have used them a bit, primo probably feels very weak... primo e feels weak to me, unless stacked, and used in fairly(very) large doses...
being that this gentleman is much older, and(sounds like) he hasn't used aas, so even something considered 'weak' by many(including me) will probably give him the little boost he is looking for.. and won't effect his endogenous test and will be much lighter on sides than most things... so IMO, he is looking in the right direction as far as his choice of aas to try... but, as most have stated, better have a good source(because it is PRICEY, and is OFTEN faked!!!)
that being said, I agree with nearly everyone's suggestion at just using test... except judging by OP post, it doesn't sound like he is trying to get huge, just wants a little boost with minimal sides and minimal suppression(especially since he probably does not have too much T running through his body anyway)...
OP, regardless if you only use primo.. do pct.... pct may well give you the extra 'edge' you are looking for in addition to the primo giving you the edge...
good luck bro, there's a lot of good advice in this thread... think about it, research it, keep asking questions if you need to, before you take the plunge...