GM's ordering process is odd in that you can order a vehicle but then it has to be "accepted" to be built. No telling how many people have "ordered" a Tahoe/Silverado/etc and that order was never built.
In order for a vehicle to be "accepted" and built, the dealer has to have an allocation for every option on your build. A dealer may get four Tahoe allocations but it may be for two LS, one RST and one High Country, and only two sunroof allocations and one diesel allocation. Other options may not require an allocation if there aren't any "constraints" on them. Back a couple years ago this was a big issue, wouldn't think that it is now but probably also depends on how big of a dealer you're ordering from...Z71s are also not as prevalent as well
think allocations were on a two week cycle...if it's sitting at 1100, ask them if they have an allocation for your order or if anything specific is holding it up (is the 6.2 on constraint?)...go down that path