Moms of toddler+ twins

Did you do 1 on 1 days? If so when did you start? Mine turn 2 soon and I can tell they are getting annoyed sharing me. I want to start 1 on 1 days but not sure what to do with them. My husband has done it before and I end up doing a park visit with the other. They act like they miss eachother when they are away but when they are together they get annoyed with eachother.

Any ideas what to do on a 1 on 1 day?