Keith’s note: according to “Senate Commerce Announces Hearing for NASA, FCC Nominees“: “U.S. Senator Ted Cruz (R-Texas), Chairman of the Senate Committee on Commerce, Science, and Transportation, will convene a nominations hearing for Jared Isaacman, nominee to be Administrator of the National Aeronautics and Space Administration … at 10:00 AM EST on Wednesday, April 9, 2025.”
Biologist, Explorers Club Fellow, ex-NASA Space Biologist and Payload integrator, Editor of NASAWatch.com and Astrobiology.com, Lapsed climber, Explorer, Synaesthete, Former Challenger Center board member... More by Keith Cowing

How long after the hearing is the vote/confirmation?
For someone like him it’s super simple and vote happens immediately after. He will probably take the oath the next day April 10.
Now the changes to NASA will likely move as the backroom handshake deals have concluded and the nomination moves forward.