When do you start to line up a contractor for your flip?

[Tim Porsche]

Hi All,

Sorry if this is a dumb question, but for those of you who do fix and flip projects, at what point in the process do you generally start looking around for a good contractor? Is it before you start looking for a project, after you start looking, when you have identified a property you are considering putting under contract, or after you already have a property under contract and are in your due diligence period? 

Most of the good contractors around here are very busy on projects, so I'm just curious how to go about making sure I have someone lined up. My concern is if I line someone up too early, they could end up becoming too busy with other projects by the time I would actually find and acquire a project. Any advice\insight would be greatly appreciated :). Thanks in advance.