I had a bit of delay on my land also (not as bad as yours). Boutique aren't quite as quick as some of the other builders but it became apparent later, in my case, that they were doing a ton of work in the background. There was a load of reports & drawings that I hadn't seen in the contract stage. You also have the building permit etc which can't happen until you have the title.
Nevertheless, 12 weeks+ to start is a really long time, surprised at that. They get paid by building so they're not interested in slowing it down. Two to four weeks after settlement is fairly normal, is there something unusual about the block?