Advice for newbie

[Marsha Rost]

I have experience doing renovations but for the first time I'm starting a new construction. I have plans that have been approved for permit. 

what is the first thing I need to do now? Do I need to bring in a surveyor to mark the corners of the foundation? 

the foundation guy tells me he needs a po to start work. Can anyone share a sample po I can give him? 

this is my first time doing this and I'm super nervous. Any help/advice is much appreciated.