R u onshore or offshore?
Aat will take upto 2 years, you should find better way, if you want to obtain a time then Aat is the better option.
If your agent assure you like your position is geniune by labour market testing, then my advice for you to aaply aat first and after 2 or 3 months apply nominnation again. I understand its cost you much but these days immigration have quite fast processing time so hope you would have your desire result.
Goodluck