Hey there, Steven, and welcome to planDisney! I'm thrilled to hear you're planning a trip for May - it'll be here before you know it!
While I can't speak authoritatively to how it works for third party vendors, when you purchase your
theme park tickets through the
Disneyland website, you make your
theme park reservations as part of the purchasing process. However, if you want to check to make sure you can reserve the dates that you're looking at for your trip, then you can look at the
Theme Park Reservation Calendar. As of the time that I'm answering this, May looks very open! You might also want to double check any of the fine print with the third party vendor to make sure there are no blockout dates.
In order to make a theme park reservation, you will first need to have a valid theme park ticket. This means you would need to make the purchase first before you're able to actually make those park reservations. However, like I said above, it looks like you should be good to go as long as there are no blockout dates with the third party vendor.
After you book your
vacation package, then it's time to plan out all the fun things you want to do on your trip! You'll be visiting in the midst of the
Disney100 celebration, which has so many fun things to do and see
and eat! Make sure to also plan some time to see
Wondrous Journeys and
World of Color - ONE - they're amazing!
I hope you have such a great time, Steven. Thanks again for your question! If you think of any more leading up to your trip, make sure to come back and see us here at planDisney.
Have a Magical Day,
Greg