Onboarding Paperwork Timeline?

New grad here— hired as an incoming associate with a start date in September at a different firm than I summered with last year.

I was offered the position and accepted about three weeks ago— during which they asked me to keep an eye out of onboarding paperwork. I have not received anything as of today.

Is this something I should reach out to the Hiring Manager about or is this more of a protracted process?