The point at which you should start to hire someone else to do that is when you, as the founder, absolutely cannot meet the demand even though you're getting up really early and staying up really late and building your investing deck on the weekend instead so you can continue to meet with customers.
Hire when it hurts, not when you can
Leadership → Org Design
We don't love the idea of hiring people based off of a hypothesis that something is going to work. That's a really good way to have to do layoffs because the plans you thought were going to work didn't work. So we always hired one person, prove out a theory, and then let them grow their team.
Within 60 days of each layoff, the CEO reported back to me, it's insane, I don't know how this happened, but the company's now operating better.
You need two sales reps hitting quota closing deals before you're ready to hire a manager for them.
The other time to do that, apart from just being maxed out, is when you are moving in to and usually up to a customer that both wants and expects to meet with a salesperson.
It is time to start working on growth when you feel like you have product market fit. It doesn't have to be totally perfect because you absolutely use a growth team to really accelerate and improve your product market fit.
To figure out your product market fit and how to distribute it, it's not something that you can outsource to somebody.