This depends on your bank, but generally you'll see the funds in your account two business days after the purchase completes. If your group completes after 5pm, it may be three business days.
In some cases when the bank is more obscure (small credit unions, etc.) then the payouts may take longer, but this is unusual. If you have not received funds after 3 business days of completing a group purchase, please contact firstname.lastname@example.org