Just some information for everyone to potentially help out.. I use to work in auto manufacturing. It's a nightmare. You're highly dependent on suppliers. Then you toss in all the variables of different configurations, different geographic locations and it becomes a nightmare. There are then tooling changes for different configs. If you change tooling too often, that's time and money, but you must change for different configs. There could be literally thousands of variables. semiconductors, seats, paint chemicals, downtime for certain robots, staffing, defects. It's endless. I think what Tesla is trying to do is provide you a rough estimate. When it slips it means something is ahead of you, which I would suspect is any of these variables. If you ordered a Red Model Y and you're in Texas, it's unlikely you'll get on the schedule until more of those are ordered.