Welcome and thanks for posting your query to HCM.
It is only one day since you have had large pimple which we say as cystic acne
. If you want the area not to leave any scar then the first and foremost thing is to stop application of salicylic acid
over it as have irritation potential so can make the situation worse. The most important factor for not leaving a scar is by earliest healing, which is possible by application of antibiotic cream with oral antibiotic and pain killers to reduce the swelling or inflammation. The dark area will take its own time (around 7 days ). Strictly follow the policy of NO TOUCH to the affected area.
Last part of suggestion for future reference is to not to squeeze, pinch or scratch any pimple as it makes more of the possibility of scarring.
Hope this information will help you.
Dr Sanjay K Kanodia