I converted my home to rental in 2018, bought in 2010. I have made capital improvements before conversion. Where do I input those to add to costbasis for depreciation?

You will add the cost of the capital improvements to your original cost basis for your property.

When computing what value to use for depreciation when converting your home to a rental property you will use the lower of the fair market value or your adjusted cost basis which will include your original basis plus your capital improvements.