Although if you use EBCI and are checking bags printing out your BPs before getting to the airport is a waste of time, paper and toner/ink. By all means check in at 24 hours to see what boarding numbers you have, but you will have those numbers if you print then or at the airport. If you have no checked bags go ahead and print as it will save you some time. If you are going to check bags, however, you can print your BPs when you check your bags and anything you will have done to print BPs before then will essentially have been wasted.