I was just wondering how long it would take for the forearms to recover as they are a small muscle group. Im thinking of training them twice a week (on arms day and back day) would that be ok?

I've read plenty of times that training forearms and calves twice a week is ok. That is because those muscle groups are recruited more in your daily activities and therefore have become stubborn requiring more effort. As for the recovery part, that more than likely varies.

I have a rule of thumb with recovery time. Don't work a sore muscle until at least one day after the soreness is completely gone. Also, soreness also lets you know that you actually did work the muscle well. If I want to make a big impact quickly, I wait one day after soreness subsides, then work it again. Usually 72 hours after the workout. Could be longer if you're a beginner.

You have to be careful when you're working your forearms with other muscle groups. But like I said, try to space out days with heavy lifts that include forearms, like deadlifts and power cleans, and days when you specifically train forearms. That is, if you do that at all.

You can work forearms a lot... same with calves and neck. Don't go to failure and you can do it every other day.