Finding the exact date is really quite simple you see, I heard this from a pretty high up at the FAA:
First you take the moon while it is in the sign of aries, then you find the angle that shadows cast from the Eiffel tower upon the park bench closest northwestern corner, divide that by the air velocity of a laden swallow, and subtract the number of fingers George Washingtons white horse had. Once you have that its just a simple matter of plugging in into the formula below for e:
1zx / [(r2-d2) + (c3-p0) / 42] + e
OR
You could just tell them now and explain that you would greately appreciate a positive review as being an ATC is something you have wanted to do since you were knee high to a grasshopper... Having had several of my people leave on similar type things, I can tell you from an employers point of view that the more in the loop we are in the better we can accomodate your and our needs... It costs money to train new people, and the most we can get out of people before the leave the better it is for us, AND your replacement, if it makes it to that point.
UNLESS that is, you are about to get fired anyway, in which case, I'm not too sure how they find out is going to matter, the result will probably be the same....
Before I even sent in my application I cornered the owner of the company I work for, explained what was going on and what I inteded to do. He wished me the best of luck, told me that he knew he wouldn't be able to hold on to me forever since I was being vastly underutilized and promised me the best review from an employer anybody could want. Since then, he has asked me progress on a pretty regular basis and seems genuinely interested in me making it!