Toritoribe, thank you so much - your additional explanations and links to J-J dictionary are, I think, helping me see my mistakes.
1. So, when he says, 「じかんは あってるかな。」, is he saying something like "I wonder if that's the right time?" or "Is that really what time it is?"
2. Thank you for re-emphasizing that this is adverbial clause. I finally found some useful info on adverbial clauses in some of my books and I think I understand this better.
So now I believe I was wrong to read this as "Then, it's time to test the small package scale." Instead, I'm wondering if it's more like "Next is the scale he uses when weighing small packages." - and given that that's an adverbial clause, we could leave that out and it would just be (as you pointed out) "Next is the scale." I'm now thinking there's nothing in there at all about testing the scale. (He does go on to weigh himself, but not to check the scale's accuracy.) Am I closer now?
3. Again, thank you so much for the pointer to the J-J dictionary. I'm still learning about the many useful resources on the Web and which ones to use when.
Thank you!