First of all, don't panic! You've got 30 weeks of Initial Officer Training at Cranwell and then another 30 weeks of Engineer Officer Foundation Training at Cosford before you need worry about your first tour.
Having said that, and this is a personal opinion, if you're Eng(AS) then set your sights now on being a JEngO (Junior Engineer Officer) on your first tour. Very few get it as a first tour, but it's a hell of a feather in your cap if you do (and don't worry, Cosford won't let it happen if you're not up to it)
And if you're Eng(CE), then I haven't got a clue what you people do...