Southern California LA Go Card and tours

[stacy~**]

I am planning to purchase the 1 day go card for our WB tour and Madame Tussauds. I *think* we can squeeze in the Movie Star Homes tour in between the two IF we can actually get on it. On the Go card website it says you can't make reservations for the home tour (although on the home tour website you can if you are paying). SO....my question is....is there ANY chance we could get on an afternoon home tour on a Saturday in July with a same day reservation?? Are these super popular?

I may have to call but wondered if anyone had experience with this here? thoughts??