Taint nothin to be afeared of old boy,, I will assume that you have a semi,, If so timing does not apply. Timing is set by the screw at the rear of your trigger lock, or if that is not present, then by bending the trigger. It "times" the bolt lock up to the time that the trigger engages the sear and fires a FA 1919,, as stated, does not apply to semi's. The head space is another matter,,, If you screw your barrel all the way into the barrel extention, and then pull the bolt to the rear, it will close just so far, but will not lock into battery. An easy way to see and feel the lock up is to unscrew the booster off the end of the jacket. With the bolt pulled back, and the barrel screwed in, slowly un screw the barrel,,,, you will see the bolt start to travel forward,, as you continue, it will close further,, all od a sudden it will clack forward and lock up,, the bolt will go all the way forward and the breach block that is a part of the barrel extension will slide up the breach cam ramp and slide up into the bottom of the bolt,,, it iis now locked into battery,,, the final head space is normally two or three clicks further out (unscrewed). At this point the gun should cycle easily and smoothly. The trigger should engage the sear and release the firing pin.
You can do this with the booster on, but you will have to hold the bolt back as you insert a small screw driver into the barrel splines and click the barrel in and out one click at a time. The only reason to go the booster thing is to see it happen in real time. You learn a lot by seeing it lock up that way. HTH,,,,, Welcome and have fun.