How long should I wait before requesting a credit line increase on my credit card?

Okay, so I started out pretty rough on my credit score but I’ve been working really hard at cleaning it up. My credit lines are kinda low on my 2 cards ones 900 and ones 2000. I want to increase my credit line so it will help boost my credit score. I am very careful now and pay everything on time and have no debt. How long should I have the card before I request a credit line increase?