This has been something that I have tried to figure out myself; however, I can't figure out where to find the correct answer.

How in the world do you sinc. your clock with ATC's in the IFR environment?

For ex: Clearance void if not off by 1930, time now 1925 and 1/2 seconds. How in the world do you sinc your clock with this. I have my methods of taking my time and using what time is on my clock and working the difference, but sometimes my calculations cannot take in the seconds factor.

Also, let's say that I report crossing the hold fix at 1101, what does ATC do when my time does not match up?

I have many, many questions like these that are really something I think only experienced pilots would probably know, this being that they have been in the environment for some time. I do read my books quite often, but all of my questions still loom.

I would like to thank you guys for the help early, I am currently getting back into the flying after 6 months of ground responsibilities! I will be starting with two Instrument students next week, and I would like to teach them as much good info as I can.