Admob ad load and multiple screen


We need use close current screen and open another screen for switching between screens.If we dont do it like this notifier not work correct.But there is a problem with it.

I want display a rewarded ads on screen 1 and i show it when user accept. I added button when rewarded ad loaded its visible to user.When he click it i ask him do you want it? If he is accept my offer i show rewarded ad.

So i need load rewarded ad when screen 1 opened.If i dont load ad when screen opened i need wait for load before show it to user.But if i load it when screen opened its increase data usage of my app.I know i dont pay for this but if user on mobile data plan its not good.

And there is another problem.If user has a slow connection and changed screens too fast i cant load any ad so i cant show him.

Is it posible add independet ad load? When app opened all ads loaded when i call them.So if user close screen and reopened screen i dont need reload ads?

Is it posible