You have a number of choices:
You can start rounding out the player's secondary attributes now.
You can get strength and blocking to the 3 point softcap (61 before equipment) as soon as possible and then start rounding out your secondary attributes, which you'd be training in the meantime.
You can bump up your secondary stats to where you think you'd like them one-by-one.
You can do a quick-build on the pass-blocking tree to get a couple of points in line-general, while training up your secondary stats.
I'm sure people can think of other strategies. Which one I'd choose would depend on whether I was boosting the player; whether I wanted him to be complete for the start of next season or the end of next season; whether he was needed by a team now or for the future; etc.