What I meant is wouldn't be better to hold on to upgrading until you get some of the better weapons in the game since there will always be better loot coming.
I would pop in that e.g. armor upgrade if it got unlocked. Especially at lower levels because they are basically free to pop in once they become available and give decent boosts to your performance.
E.g. Jeff hasn't got that much upgrade gear between level 1 and 7 this far and he is doing normal story + patrol stuff. So upgrading existing gear would be good option for him.