David Letterman has set a date for his departure: He’ll host his CBS Late Show for the final time on May 20, the network just announced. Letterman’s last show will air on a Wednesday rather than a Friday, making for a shortened final week of shows. CBS didn’t explain the reasoning behind the scheduling, but here’s one possibility: Had Letterman left on a Friday, his last show would have been on May 22 — exactly 23 years to the date Letterman’s idol, Johnny Carson, stepped down as host of The Tonight Show. While there would have been some nice symbolism there, Letterman might not have wanted to seem as if he were taking anything away from Carson. That Friday also happens to be the beginning of the Memorial Day weekend, so CBS might not have wanted Letterman’s exit to get lost in any holiday shuffle. What’s more, May 20 is also the last day of the 2014–15 TV season, so a Wednesday exit means the big ratings Letterman will draw that night will get counted in his show’s average for the season. Letterman will have hosted 6,028 episode of Late Show and his NBC show, Late Night, when he departs.