When do you know when to start hiring?

Don't always assume that just because you're running around like a chicken without a head, that you need to hire more employees. Try determining what every employee should bring in monthly. make sure you hit that goal consistently before hiring more.

for example, if all of your employees do the same services and hold the same position, and you expect each one to produce, lets say $30k per month, then you would not outfit a fourth truck until you were consistently reaching or exceeding $90k a month.

you may find that you are super busy, but it may be due to inefficiency, routing issues, new guy mistakes, and follow-ups. the way to confirm you are on track is by ensuring each truck is making what it should make before growing.