How many days prior to my payment due date, should I be receiving my monthly mortgage statement?

No specific timeline required by Respa, but lenders usually want their clients to have the statements as soon as possible. Many will forward the next statement as soon as a payment posts (ie: make the Dec payment 12/1, get the Jan statement shortly thereafter). You certainly should have the statement before the end of the month. Keep in mind that mortgages have a 15 day grace period before any late fees accrue. As long as your payment is posted by the 15th, it’s every bit as good as if it posted on the 1st.