Preview prices range from $38 to $76. The preview period is as follows:
Friday, Saturday, March 24 and 25 @8pm; Thursday, Friday, March 30 and 31 @8pm; Saturday, April 1 @2 and 8pm; Thursday and Friday, April 6 and 7 @8pm; Saturday, April 8 @2 and 8pm; Wednesday - Friday, April 12-14 @8pm; Saturday, April 15 @2 and 8pm; Tuesday - Friday, April 18-21 @8pm; Saturday April 22 @2 and 8pm; Thursday and Friday, April 27 and 28 @8pm; Saturday, April 29 @2 and 8pm; Sunday, April 30 @3pm; Tuesday, May 2 @8pm; Wednesday, May 3 @2 and 8pm; Friday, May 5 @8pm; Saturday, May 6 @2 and 8pm; Sunday, May 7 @ 3pm; Monday and Tuesday, May 8 and 9 @8pm
It's toward the weekend, but it depends on the week. There's one week in April where they do go Tuesday-Saturday, but then the next week, don't have a performance until Thursday again. By May, they're into a normal schedule.
Interesting that they start previews on a Friday, have a show Saturday, and then don't have another show until the next Friday.
If you are felxible you can probably still get some sort of ticket for a day during previews, but they are almost sold out for the first couple of months