How long is it gonna take to see the final result? How often should I use this and can I use this on my neck? (Photo)

I am filipina, not happy with my skin recently. I get more acne now than usually, the pores around my nose is larger than i remember, i have discoloration also specially on my forehead and around my mouth and chin. So my question are, if i start with 30% of glycolic acid peel, how often should i do this? And i wanna do it on my neck as well just to even out my skin tone, can i use this on my neck and should i use the %50 for my neck?