Validity and duration of stay

If I get a 60 Day tourist visa, with a 6 month validity, which is issued at 10 Nov 2018 (and expires 10 May 2019), could I enter on 10 April and use all days?

Validity would expire on 10 May, does this means I have to leave by then and can't use all those extra days?

I'm asking this, because I will backpack 3.5 months, before coming to China for 2 months. I would like to arrange the visa in my home country and not abroad.