My players were recently in a large scale battle and the Dominion got re-enforcements so they decided that the battle was lost and retreated.
In terms of actions how long does it take to go to warp and under what conditions does the ship need. I used one action of no movement or firing before they could go to warp. I am sure I have read it somewhere but I can not find it.
Don't recall any listed rules, but I'd say probably just your action for the turn. A ship can engage warp pretty fast assuming it's at full functionality. Look at Voyager in Scorpion, Part I. The 8472 ship fires and knocks the ship tumbling. Almost as soon as it comes out of the spin, it jumps to warp. Sulu got the Enterprise up to speed FAST in Wrath of Khan once the mains came back on, and in The Final Frontier she was fast enough to avoid an incoming torpedo that was already en route when Chekov gave the order! The time taken for a ship at maximum efficiency to engage engines seems to be not much faster than the length of time it takes the helm officer to press the button, plus a few milliseconds while the computer runs safety checks on the immediate course.
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"Spatial anomalies, energy beings, telepathic echoes. You know, sometimes I really miss the Dominion War. At least then all we had to worry about was where the next polaron beam was coming from...": Capt.Hunter, USS Tempest
My rule of thumb: takes a turn to prep and make the jump normally, BUT...if you need to just pop the clutch, you can. I require a reaction roll from the helmsman vs. 8; and sometimes a warp engineering rolls from whomever of the same to make sure nothing goes 'clunk'.
I'd also say they you'd need a clear path for going to warp. Normally this isn't much of a problem, but in a fleet engaagement a ship could concievably find it flight path blocked by a ship or torp cutting acrros her bow.