My friend's birthday is in 20 days. Can I give him a birthday present in advance now?

Yes, isn't there a saying that "a goose feather is sent a thousand miles away, and the ceremony is light and affectionate"? What's more, your birthday present is not light. You just want to share your happy birthday with your friends in advance. It is important for friends to communicate with each other. You've already done that. As for before or after, it's actually just a ceremony. Sincerely wishing each other is the warmest friendship.