I'm sure the pre-production of Popmart was in planning within a year of when POP was released. Making it possible to to include in the album art. Plus, U2 started the Popmart tour less than 2 months of album release.
Because Pop was a disaster in planning. The tour was booked way before the album was done, so the tour was planned while the booklet wasn't even in print yet.
The Pop booklet is my favorite, best one by the band.
A funny sidenote; in the Pop booklet photos, Adam has a deep tan, and when I first got into U2, I was Maybe 13, and I only owned The Joshua Tree and then I got Pop, I thought to myself, "Oh, they must have replaced the basist with a black guy, cool!"