There is no set time-limit for the app review/approval process. It depends on a lot of factors but mostly, it can take anywhere between 5 days and 4 weeks. Sometimes, if you don’t activate the IAPs, your app might remain in pending for a long time till you fix it.
There’s nothing technical you can do to get your app reviewed faster but if you follow these steps, you might avoid getting your app rejected and follow the reject-repeal cycle.