to add to what they all have stated.
remove a rear cylinder spark plug, so the compression from the rear cyl does not interfer with the rotation of the motor.
you should now be able to feel the front cylinder on the compression stroke as you bring it to top dead center.
you should also watch the rockers, as you come up to the FT mark,
there should be no movement of the exhaust rocker if you are on the compression stroke. as you pass the FT mark, there should be no movement from the intake rocker.
as stated you will adjust both intake and exhaust at the same time with out turning the motor, then do the same with the rear cyl.
you want just a little drag on the feeler gauge after the lock nut is tightend down. but you should not have to force the feeler between the valve and rocker, should go in nice and easy.
if you are 360 out of DTC, as you near the FT mark, the exhaust valve will be closing, as you pass the FT mark, the intake will start to open.
hope this helps you in some way.