When should I do my 301 redirect?

I'm moving a website

[The Cricketer]

I have a site (SITE A) which is 2 years old and not doing too badly in the search engines. It is a plain HTML web site. It uses web space provided by my ISP and has an externally purchased domain name (www.example.co.uk) pointing to the home page (wwWebmasterWorldebpage.isp.com) of SITE A.

I have purchased web space for SITE B at a different host which will use the same content as SITE A but it will be stored in a database (php/MySQL). However this database and the php pages are currently still in production and will not be ready for a couple of months.

I want to make the transition between the sites as smooth as possible and it looks as if a 301 permanent redirect is the best option, but do I

1)copy all the SITE A html pages to SITE B now, change the nameservers of www.example.co.uk so that the whole of SITE B uses www.example.co.uk. And then implement 301s for the site, redirecting to identical pages but on another server (SITE B).

or

2)wait until I have produced the php/mysql site at SITE B and start all over by changing the nameservers of www.example.co.uk to SITE B. No 301.

or

3) wait until I have produced the php/mysql site at SITE B and change the nameservers of www.example.co.uk to SITE B. Then implement some kind of 301 redirect?

Your thoughts please!

[goodroi]

I would vote for b.

In general avoid having duplicate content at any time. Also minimize your use of 301 redirects, in other words you don't want to 301 redirect to temporary pages and then a week later 301 redirect to permanent pages.

[synergy]

No matter what option you choose, be prepared to be 100% gone from Google for at least 3 months, and possibly held below top results for major keywords once you return.

[The Cricketer]

good advice cheers.

why is life so difficult?

You don't have to answer that.