I think with Fighter Ambush you need Boosted Comms and flying out of the gate. The objective prevents any planning and reaction from your opponent, so you need to utilize that on turn 1. Rhymer makes the best use from this because you don't need a squad command to get Tie/B in position. Just position so you are unobstructed and fire away.
I see this objective being used most effectively on an ISD I going speed 3 with FC, Boosted Comms and Expanded Hanger with Rhymer. Throw in some BCC and you're good to go.