How long does it take to transfer from National Guard to Active Duty?

Go talk to a recruiter immediately. The sooner you start the process the quicker it will be.

To expound further on Maj. Rivera's comments. To get the ball rolling, find an Active Duty recruiter and get a DD368 Conditional Release. There is a portion of the Form they should fill out, then you give it to your chain of command. The form needs the approval of the first General in your chain of command, or his designated representative. This is where the waiting begins and be aware that they have no requirement to release you. Financial Hardship is a valid reason, but it may depend on how short handed they are and just how long that you have been in the Guard. My experience in the past that it gets easier that closer you get to end of your Guard enlistment.
It may be quicker to find an ADOS job without leaving the Guard.

Few steps in the process:

1. Contact a recruiter right away!!!!!
2. You’ll need a DD Form 368, Requests for Conditional Release. This last one is where the black hole comes. Your NG unit leadership, at what ever level it’s held, need to approve and sign that puppy before you can move forward.
3. Once that’s done, it will be based on the current USAREC’s Business Rules. Remember, you’re prior service.

Best of lucks on your endeavors!