The USPS does not give a set time for how long standard mail (bulk mail) should be delivered as they process the mail as quickly as they can but first class mail always takes precedent. Standard mail can take anywhere from 1 to 27 days to be delivered sometimes even longer, but typically we see 3-15 days.
Delivery times depend on where the piece is going, the type of mail piece, as well as the time of year and work load of the postal service.
Below is a map from the post office indicating the service standard delivery times, but these times are not set in stone. These times are from the originating post office in San Diego, but depending on your database we can deliver to Los Angeles or anywhere in Southern California or drop ship anywhere in the country to expedite delivery times and decrease postage.
For time sensitive piece is it best to send first class mail which will take 1-3 days to be delivered, but the postage costs are much higher.
It is difficult to predict deliver times on standard/marketing mail but the best option is to use the map above and ensure that there is a few day buffer. You can also track your mail to get a better idea of the delivery times, but keep in mind that each mailing may have different results depending on the time of year and how the USPS work load is looking.