Unfortunately not all venders updates the progress of their GBs to the same degree, so I find that you usually have to cross check a bunch of venders, if that doesn't work I check the geekhack GB thread for the set, and if that doesn't go anywhere I see if the designer has a discord and go there.

As for GMK Lavender itself, like people have said it's being shipped right now (my vender for the set, Ashkeebs, is currently shipping it). I actually expected the set to ship much later in the year but GMK has been doing well chugging through their backlog. If you're worried I suggest you talk to your vender, I know you don't want to bother them but they're really your only point of contact for what you have bought so just go ahead and do it next time. The worst they can do is ghost you.