The biggest thing you need to do is change your mindset. It doesn't matter what you get done, it matters what your team gets done.
This doesn't need to be all that hard. Give a person a problem that needs taking care of, make sure they have whatever they need to get shit done, and let them go do it.
Two other notes, just because I strongly suspect you're going to run into them:
1. Onboarding is hard work. It takes time. You're not going to be able to delegate everything on day one. Start with one thing, then add another, then the next. In some cases, the only way to ensure someone has enough context it take the problem over is to pair on it for a while. This is time consuming, but its an investment.
2. Being a solo dev for a long time, you might have strong opinions about the right way to do things. Your team isn't going to want to do everything your way and can't read your mind. This is a good thing, the team's collective brain just got bigger. Embrace it.
I've also found just being human goes a shockingly long way. If you're honest, share information, and treat people with respect, it turns out they'll like working for you. This really shouldn't be a surprise, but the bar is quite low.