I got recommended by the panel to get an opportunity to join the AGR Program. How long before a decision is made for an assignment?

If you were selected by the board, you will get an assignment shortly. I was boarded in March, Notified in May, Had Orders in June, and Boarded in July.

I got same situation, the panel is OCT 22-26, does that mean they will give me an assignment during this time?

It can vary. I never got "recommended by board" status online. It took about two weeks after the board week and got an offer 2 weeks later. I sent the acceptance paper work that same day and got a second email two days after. The second email was the financial packet. I sent that two days later. Then after o had to enroll my daughter into the EFMP. That took the longest to complete. 3 weeks later after receiving the offer email, I'm still waiting for my orders. Come this Wed. Dec 5. it will be a month since I started the process. Thst will leave me 1 month to PCS and show up to my new duty station. The bad thing is that I cant get anything started without my orders, especially trying to set up an appointment with the Transportstion Office. I cant make an appointment online without getting the orders first.
But to go back to your question, it can take a day, a week, a few weeks, or a month.... there's no set time. I kept reading about it on the internet before I finally got my offer.

Just be patient. This whole process has been testing my patients... It'll really be tested next month when I'm trying to get everything done within less than a month.