04 sentra se-r spec v timing issues

I am trying to check the timing on my qr25de motor but i cannot find any information online anywhere as to how to check it. only how to replace the entire timing set. ive already had it replaced at a shop and i suspect its out of timing but i cannot find any local shop that will come to me. thus i am limited to free options in my own driveway as to checking the timing. i was informed that there are marks on the timing housing that indicate where the cam sprocket and vvt sprocket are to be aligned every 2 turns of the motor. however i can only find the marking for the vvt. the one on the cam sprocket isnt there. so again i am back to having no way to check the timing on the car without pulling the entire motor out to remove the timing set and start over from scratch.