Question about stretching

Hello,

I’m new here and I’ve got a question about stretching. When I place my hand behind the head of my penis en pull it down how much sqeezing force can I apply (against slipping) before it is going to effect my penis in a negative way?
Is stretching done fully erect or also 80% erect?

Stretching is done FLACCID, unless you’ve been pe’ing for a long time. All newbies, including myself should stretch with 0% erection.

Fitman