You'll have to make sure enough time is on both accounts(your main and the one containing the name you want) to switch. Once you get the account with the name you want, you switch it's name and be sure to remember exactly when, because about 28ish days later is the earliest you'd be able to get it on your main. I
wish you luck though because there are some serious name hunters out there, so I'd advise you to not name what you are looking for. :x
Btw, I'm pretty sure "Dave" is active atm, so you might want to cross that off your list.