FWIW, I just skimmed the FOTM. "The student is required to possess a multi-engine ATP Certificate, an ATP Certificate with restricted privileges, OR a Commercial Pilot Certificate with airplane multi-engine land..."

It looks like our approved FOTM allows for hiring a pilot without an ATP, however, minimum qualifications listed in job openings call for an unrestricted ATP. In order to be competitive I would apply after receiving an ATP. If you want to roll the dice, though, go ahead and apply without. Evidently we have hired some without the minimum required ATP.