At what stage should I approach a business mentor to join my company?

I have an internet business that I am going to pursue. I am just at the Business plan stage and putting together my team. I have got an excellent internet entrepreneur in mind that I would like to approach to join the board as a mentor / advisor, however am I best approaching him at business plan stage with a team in place or wait until we are at beta stage and then approach him when there is a working protocol to show him?

*One point is that he owns a company that does full web development / SEO etc within this particular sector, however I am going to have a technical co-founder to develop the website.

Any thoughts on best approach as this man would be invaluable to get onboard.

Kevin

Mentor or partner?

Approach immediately. If they say no, ask them what they would have to see to join the company. Then keep them posted on milestones.

Off the top, I would wonder why a person in the business of charging for full web development would consider spending time providing non billable advice AND not get the business.

You would need to provide tremendous incentive to counter this reality.

At this stage, you should spend more time on validating the business assumptions / customer demand / willingness to pay before getting too heavy on the coding / framework / infrastructure tasks. Once you have customer validation, then you have something that he can work with / provide a technical perspective on.

In my opinion, it doesn't hurt to ask. As the saying goes: "The only dumb query is the unasked query", regardless what it pertains to. Just be careful not to give too much information away pertaining to your concept.