From experience, part time / contractors for early stage startups are usually counterproductive. They just won’t be committed, loyal, and giving 120%, while incurring massive management overhead. Don’t believe I’ve ever seen a success story.

Proper full time employees or don’t hire at all.

If you approach hiring for your startup with a "let's get a contractor" mindset, as opposed to "let's get a suitable person to work with me on this specific project" then it's no wonder you get disappointed.

If you get random people off the street, don't be surprised they don't fit.

Type of contract doesn't matter.