I made a new site for a client that is a huge improvement in terms of asset optimisation, page loads, on-page SEO etc. Rather than use the existing domain that has decent authority he wants to move to a new domain that better reflects the direction his business is moving in. We registered the domain very recently so it has no presence, no authority whatsoever.
Frankly, I'm concerned that hitting the button on this is going to really slow his business for weeks, possibly months. In the long-term I'm confident he's going to see significant improvement but how can I avoid causing him harm in the short-term?
My strategy is to have both sites live simultaneously while the new site is indexed and then 301 re-direct each URL on the existing domain to the most relevant page on the new site. I'm also trying to update as many existing backlinks as possible with the new domain - for example those backlinks that are from directory sites rather than blogs etc.
I'm also thinking this is the best time to push a backlinking strategy to mitigate any damage while things sort themselves out, but I have concerns that if I approach that too aggressively it could have the opposite effect and compound the issue.
I've had decent success with SEO in the past but this is new to me, any advice would be appreciated. Aside from my professional reputation I really like this client and want to look after him.