Hi there Elisa, and welcome to planDisney! We're so glad you're here with your great planning question.
I have good news Elisa, you can purchase
Disney Genie+ Service each day as soon as you scan your tickets at the main theme park gates. As soon as I scan in, I immediately open up the
Disneyland app, and there is a button towards the top of the page to purchase Disney Genie+ Service for the day. As soon as you purchase, you can navigate to the three bars icon in the bottom right-hand corner and tap on the "Tip Board" where you can browse the list of attractions and book your first
Lightning Lane selection. I do recommend booking your first Lightning Lane selection as soon as you can to take full advantage of the helpful service. We usually select
Indiana Jones™ Adventure in
Disneyland Park or
Guardians of the Galaxy - Mission: BREAKOUT! in
Disney California Adventure Park as our first Lightning Lane selections since they are some of the more popular attractions.
For the two days that you'll be visiting with your husband, you can purchase Disney Genie+ Service for both of you as soon as you enter the gates as I mention above, and for the day that you're coming alone, you can just scan into the gates and enjoy your day. I do love a solo Disney day, especially when I get to pick out all of the attractions to ride and the snacks I want to eat!
I hope this information was helpful for your trip planning Elisa, and I'm wishing you a wonderful visit to the "Happiest Place on Earth!"
Have a magical day!
Melissa