When to start hiring sub-contractors?

I'm in the content production business. I get paid to write evergreen, editorial articles for enterprises that range anywhere between $1k-1.3K an article. The way I see things, if I'm able to produce 3-4 articles per month I'm in a good spot. That would require me producing 2 articles per client. I think is doable, since both clients have the budget and are eager for good content, even if it is "expensive."

I didn't mean to be in this business, and sort of fell into it by necessity. I used to charge $300 per article and those days were terrible, so I'm glad to be at the point I can charge $1.3K for my services after having done this 3 years or so.

I guess what I'm trying to figure out is when is it time for to start to put together my own team of writers? I think I could pay them $350 an article, and would only require a rough draft from them on their part. I would also give them a content brief but I would totally be open to paying them more assuming I can get my hands dirty too with the the articles.

I've never hired someone before, or had a sub-contractor, but I think I need one to run this content-based business effectively and I'm worried without one I will be overwhelmed as I've already seen thats the case sometimes.

How do I take this next step? I'm worried as soon as I do, the unpredictable will occur, but that's not a good way of thinking...