really? that's been my theory throughout this. how else would gambit know who had the baby, when not even sinister or the x-men did? im guessin gambit helped cable survive the explosion on providence and that he alerted cable to the baby's location in alaska while he and the marauders were en route. and im also very intrigued as to what the hell "one minute before dawn" means.
Guesses without evidence are meaningless, and are with even less meaning when evidence disproves them.
Sinister did know who had the baby, before, I think, the Cable page was revealed to us. Else it was the issue after. I doubt the information came straight from Gambit, and if it did, and he was in league with Cable, why would he have told Sinister? Rather, Sinister knew, and told his underlings, and Gambit in turn told Wolverine.
Gambit and Sunfire got the flock out of Providence when Cable set it to blow. Gambit didn't help Cable get off Providence. Cable got himself off, through some means - probably some last ounce of power to teleport or time-jump or something, some last wisp of Greymalkin.
In a way, Gambit did alert Cable to the baby's position, and that was through the initial clue he gave him on Providence. The chances the two of them had any dealings past that are very slim, slimmer than Cyke, and Cable would have gotten to the baby first based on unraveling the riddle of the clue.
"One minute before dawn" was the aforementioned clue. As for what it means, it essentially symbolizes, at this moment, the entire game plan Cable has been working off of before Bishop peed in his cheerios. The clue led to Cable solving a riddle which in turn gave him this game plan. And now we're onto Plan B.