Ummm...could you give some more information on what exactly you want to do ? I’ve read and reread your post several times and I don’t get what type of the information are you looking for,
It really depends how the team have coded it. Some allow for straight typing into a textbox then validation once that loses focus, some require every number to be scrolled through… each date picker component is written different & you’ll likely have to come up with custom code to interact with the one your app is using. It’s unlikely you’ll get code to copy-paste here & you’ll need to investigate whether your GUI allows text entry, clicks, scrolls of the finger, voice commands or a mixture.
Some of the work you might be able to offload to lower-than-GUI levels as well. I.e. if there are any API calls allowing you to pass in several arguments, one being a date, or pre-populating of a database with entries including the date?