Have a question about extenders need advice pls

Hi I recently bought an extender. I only found pro extender in my country so bought it but cd of the extender doesn’t work. So I have some questions about extender

1. My BPFSL: between 15,1 and 15,3cm

1 my BPEL:14,1cm without edging if I edge and measure I’m sure it’ll be 15,1 because my NBPEL goes 12,5 to 13,5 after 15-20 min edging and I measured my NBPEL 12,5.

My question while in extender how long should my extended penis be?

I measured from bottom to tip of the glans and I can extend with extender to around 15,5with 900grams of force.

Sorry for given metric measurements.

Which measurement should I care for gains while using extender ?