First of all, Congrats on you approval and welcome to Navy.
As far as second cards, that may not come until you hit your 6 month mark with the one you have. I would wait and try again then
Congratulations on your approval. NFCU is an awesome credit union.
I'd probably wait 6 months but you can always do an emessage to recon. You've already taken the additional HP so it wouldn't hurt to ask.
Nice approval! Congratulations!! Maybe go for the CLOC as well!