Based on the depth of 15bbs it is probably best to simply shove All-In right away with AA or KK. It doesn't give the chance for something like an Ace-rag to see the Flop cheaply and bust our KK when they Flop an Ace when they would have folded to our preflop shove.
However, in a few spots against the right opponent - you might be able to open-raise and then go All-In. Perhaps against someone wary of calling All-Ins but with no issues about calling an open raise, or perhaps against someone constantly shoving over your open-raises but folding to your original raises.
Generally speaking you won't have these trickier or less informed players though. Usually I'd shove preflop instantly. Whatever you decide for this spot though, stick with it. Another reason to shove right away is because we probably don't want to open-raise with so few big blinds and then fold later in the hand. If you are committing all of your chips, then why not just do it right away? Why wait? As long as you can get it all in the middle, or extract maximum value, then it doesn't matter a ton, so might as well go in earlier to get some fold
equity along with it
Summary: Usually shove All-In for this spot, but a few tricky players or spots may come up where otherwise may be justified.
We aren't typically wanting to raise and then fold here. Why? Save a few chips...save it for what? Might as well get it in when we are almost certainly ahead.