The poster and handbill for these shows both have errors on them leading to confusion as to when these shows took place. They are from 1967, not 1966. I found a newspaper article to confirm this. See the poster info here.

The newspaper article is from Sunday March 26, 1967 and says Charles Lloyd will be playing at the Rock Garden "tonight, Tuesday, Wednesday, Friday and Saturday. The Grateful Dead and the Virginians, a pair of r 'n' r groups, will share the bill." The poster says Mystery Trend will be playing, but the article says The Virginians instead. Whoever did the poster and handbill really screwed them up. Since the newspaper article was published the day of the 1st show in the run, I suggest going by what it says only. That means the shows were on March 26 (Sunday, "tonight"), March 28 & 29 (Tues and Wed), and March 31 & April 1 (Friday and Sat).

Teddy "GoodBear" Selby (May 2011) -
It's obvious to me that the posters and handbills are misprinted and/or possibly fraudulent. The fact that they say, "April 28th-March 2" indicates that.