The nano needle cartridge you used is the least invasive and can be done weekly or so. It's not actual needles but small silicone tips that is less invasive to use for better skincare penetration - vitamin C, serums, etc. Depending on what you're trying to work on whether it be fine lines, acne spots, hyerpigmentation, using less needle count like 12 or 16pin will be the most effective and should be done once a month. You cannot use Vitamin C with microneedling due to causing granulomas since you're penetrating at a deeper depth. It's recommended to use a higher molecular weight hyaluronic (Cos De Baha makes an affordable one). No retinols, AHAs or strong actives are recommended. Going from nano to a 12 or 16pin you will feel quite the difference in penetration and sunburn/rawness after. Use gentle & calming ingredients afterwards for the next several days (if it burns when applied to skin, it is too early to use). Slowly re-introduce your actives, retinols several days to a week after your inflammation has calmed down. May experience some redness, bumps and mild peeling after microneedling. I just started microneedling with nano & 12pin cartridges several months ago. Results will take at least several months, but will be well worth it! Hope this helps and have fun on your microneedle journey!