One Month..............
Your whipped and I'm betting you aint even been there yet.
Seriously, when this relationship fails, and it will, that $50 you just blew on flowers or whatever it is that you buy her will seem really stupid.
Forget the letter, just drop her a call and say "Hey I just realized we had our first date a month ago today, so when are we getting together for our next" and let it roll from that point without getting caught up in all the drama. Ensure the phone call comes from a place like the mall or while your at work, maybe in-between clasess. Make it look spontaneous rather than planned. Girl gonna think your some psycho stalker smothering kinda guy if you start showering her with gifts and crap at 30-days.
I know you will not follow my advice but in 5yrs after you have been aroound the block a few times you will be kicking yourself for not following my advice and other guys advice just like this.
And Yes, I Dr. Phil, have approved this message!