At-Home TCA Peel for Rolling Scars- What Percentage and Duration Do You Suggest For Asian Skin?

I from shanghai,China.I had a bad experience treatment in China I decide to help myself,I have large area rolling scars.I researched tca from internet,I performed 25% tca two times( big area)Q1:How long keep the solution on my face?30sec or 1-3 min?When I see the frosted I should neutralize it,not completely white right?Q2:Some rollingscars on myface is deep,should I do another layer or apply stronger(like 35%)? Q3:Two layers 25%tca equivalent to 35%?Please answer just for tca and rolling scar