> How many net & total grams of carbs a day

Total grams doesn't matter. The point is the glycemic impact. Some people are very sensitive to carbs and can't eat a banana without throwing off ketosis, and others can have upwards of 30g of net carbs a day and still stay in ketosis. My goal is 20g or less, and my ketones still stay in the 1.5-2.0 range unless I overdo protein instead of fat.

For most people, the starting point is around 15g net carbs a day. If you're serious about keto (and staying healthy while doing so) you'll want a ketone testing mechanism as well as guidance from your doctor about adjusting medications since ketosis mimics a fasting state for a bunch of your metabolic processes.