The Yankees aren't offering any official time-tables on Derek Jeter, because that is how Jeter likes and, probably more importantly, they really don't know. Jeter's ankle recovery is explained succinctly by our own injury expert, Stephania Bell.
Jeter is currently working out in Tampa doing baseball drills and, most importantly, progressing his running from water to land. The team (wisely) will not hear of his return until he can play in minor league games on back-to-back days, something which is still a ways off. The Yankees are not being coy about a timetable here; it literally is a stepwise process where the next level of activity is dictated by response to the previous level. Jeter is literally as day-to-day as they come, but based on what he is currently doing it appears like early May is in his sights.
So basically, Jeter has to advance past each level before he can return to Yankee Stadium. So he could be back in three weeks or so, but it just as easily could be longer.