Preservation Hive Mind:Canning Question

I am looking at my tomato sauce and wondering if maybe I did not hot-water bath it long enough. I think I might have looked at the pressure-canning times... or just spaced...

Can I put the jars into the water bath, heat the water, and start the timing when the water boils?

Or, do I need to open the jars, wash them, get new lids (again) and start from there?

Help?

Pressure Canner

Does anyone have a pressure canner they would lend/long-term loan/give me?