Well,.. as said previously.. if you use it wise you'll benefit from it.. .Start from low to high. Its obvious everyone wants to get the result quick, and many people ends up having severe side effects like skin discoloration and scarring. For acne scars there are preparation ranging from 20- 70% glycolic acid which can be applied every 2-3 weeks. Don't just go for online products that have higher AHA or promise to clear acne scars within a week, thats not gonna happen, it takes time and patience.
If you are planning to apply AHA peels i would suggest to get a consultation from a dermatologist or any Experts personally. See.. if you have any allergic history or give it a trial on your wrist or sth..before applying.
What i would do is: Go for less concentration AHA creams or lotions (less then 10%) rather then peels and would apply every other day for 2-3 weeks then daily at night. Remember to avoid sun and use regular sunscreen. I would start from around 3%- initially and increase to 8% then to around 15% .
So as Retin A gel is concerned, i would alternate between these two every other nights. And yes its safe to use both during night alternating every other night. But as most important Avoid sun, use sunscreen and go with low concentration, gradually increasing as desired.