If I'm remembering correctly, you have another cat. Based on that, I would get another one, whenever you feel ready. Your remaining kitty would probably love the companionship, although don't expect them to be all lovey-dovey at first. It takes time. Last time we got a new kitten (showed up on our doorstep), it took ~2 weeks for the dog to accept him, maybe 4 weeks for the older cats.
Please give consideration to adopting from a shelter. And know that black cats have the hardest time getting adopted, but they have great personalities. That said, go when your heart moves you, pick the kitty who touches you. Don't let anyone tell you that there's a right or wrong time to get a new kitty.