You can't "tell" the grading companies what date it is for blanks or planchets. You would literally have to send them in an unopened Mint set in the unopened Mint cello (the cellophane envelope or the sealed hard plastic proof sets that must be broken to open) or a Mint-sewn bag of coins and let them unseal it themselves that are with other coins having the exact same date. Do I believe the OP that it was in an original roll? Yes. Do I think he can say it is a 2007 despite not being struck? Yes. Will the grading companies do so? Not with the roll unsealed. The other way a specific date can be determined is if a new type of blank/blanchet is produced and submitted the first year it comes out. For example, @Fred Weinberg has an unstruck Sacagawea $1 planchet on his site (fredweinberg.com) dated "2000." How can that be? And if the Presidential and Sacagawea $1 coin come from the exact same planchet, why can't it also be a Presidential dollar? Answer: Because it had to be submitted sometime in 2000, the very first year the Sac dollar was made. Also, the Presidential Series didn't start until 2007. Therefore, the 2000 date and the type (Sac vs. Pres) can be attributed despite not being struck at all.
Yes, I made sure that every Planchet for the Sac. Dollars that I acquired during the first year of it's issue, was submitted to PCGS (or NGC) before 12/31 of 2000. That's why some (very very few) have the '2000' date on the label.
I wasn't saying the OP should send in a $2 blank for grading. I said it was cool that he was able to date it, and to put it on a 2x2 flip.