Which day of the week is less crowded?

I would say, any day of the week.

Thursday at 5:00 is usually their slowest time. Usually.

Just don't go right before Halloween and you're solid.

I went on a Wednesday at six and walked right in

They have a pretty good system going and the wait anyday is around 20min

Any day any time. Hit or miss, generally about a 20 minute wait

I was there on Monday about 1pm. The wait was about 20 min. They go in groups of 12. Hours are 1pm to 9pm. I waited for about 20 min. Not bad, it was nice chatting with the other people in line.

We got in about an hour in a Sunday. Wasn't bad at all

Sunday Monday Tuesday Wednesday Thursday Friday Saturday

It's fairly steady, but not like you won't get in. The whole experience takes a little over an hour so budget about 2 to 2.5 hours total just in case.