I am not sure, went to two different Maxis center and I got 2 different answer.
But the answer I got from call center 123 is 30 days, which is close to one month.

Yea, so far for my Maxis legacy postpaid plan, the route is Hotlink Prepaid first, then to Hotlink Postpaid.
This route has to be done via 123 call center.

So I came across Hotlink postpaid plan which has affordable plan.

https://www.hotlink.com.my/en/products/postpaid/

Question is, can I switch from Maxis Postpaid plan to this Hotlink postpaid plan while keeping my number?