Yes most all banks post funds from cashier checks and money orders the day you make the deposit, especially if your account maintains an average balance greater than the amount of the check or money order. The reason many people wait for a period of time prior to shipping the goods, is in case the cashiers check or money order is counterfeit.
At times, dishonest people have been known to purchase a real money order with a real serial-number for low amount, and then carefully bleach out the actual amount and reprint the new fraudulent amount. From what I understand, done correctly, it is difficult to tell if the money order is is real or fake. In this case, the bank takes the money order in, posts the amount to your account, and then when the fake money order is actually reconciled by the issuing company, a charge-back is sent to the bank which is then charged-back to your account. Ouch!
