Rented a property for a decade but never took property depreciation?

We've been renting out a residential property for about a decade now. However, we are just learning now about the ability to take depreciation against that property's value. This was never suggested to us by the TurboTax software annoyingly enough.

 

If we didn't take any depreciation during this past decade, can we start now? Or are we stuck?

 

Of course we plan to talk to a professional directly about this but wanted to get some initial insight.

 

Edit: Ok I did some more searching for previous answers and found similar questions. However, I still am a bit confused.

 

Do I need to file an amended return for last year to include depreciation last year and include this year's depreciation on this years return? Or do I need to file a Form 3115 before doing anything at all, including filing this year's taxes?