I struggle with premises and first sentences, but I always tell myself that it's a word-vomit draft in November. I don't have to know the first sentence. Last year's project was such a lovely mess I only recently FOUND the beginning scene. Tweaking the first sentence... uh... now because I need to take it to a workshop mid-November.

For October, I worry my idea won't gel together completely, but it seems to be rolling fairly smoothly at the moment.
For November, I worry I won't have enough time to sit down and write the entire novel like I want to.

I always worry I've bitten off more than I can chew, too many irons in the fire, add other clichés of the too-busy kind here. Yet I manage quite a bit of it. Then I worry I'm not spending enough time with my kids!