Two Week eCommerce Site Migration - how to handle visibility

[WMCA]

Good day All,

We have a eComm site with over 100K pages and migrating to a new site design, new CMS and with a new URL structure for top level URLs only. Product URLs not changing (thank goodness!).

We have outlined our strategy for redirects, indexation, 404s, etc. The missing piece of the puzzle is that we're only allowing 10% visitors to see new site at launch and increase visibility over two week; therefore, my question is do we not allow indexing of new site until 100% visibility to all users? How do we manage the redirects for limited visibility?

My gut says don't bother for such a short period of time and block new site from SEs until 100% visibility. Since the site would be blocked how are redirects managed? Should we be using a 302 initially then switch to 301 or use a 503 code to indicate "hey, maintenance happening - come back later" with a time frame?

Hope that's clear and any tips greatly appreciated.

Cheers,

WMCA

[Inductive_Automation]

May I ask why your only allowing 10% to view? Is this a way of A/B testing the new design?

Regardless, you'll want to keep your new designed pages Noindexed, nofollow until you are ready to push them live as a whole.

How many of the top level url's are you changing? From my experience, 301'ing a large amount of pages will result in a loss of traffic. If you can manage and spread them out over a time period you may have better luck.

[WMCA]

Ideally, that's what I would have done. Have new site on a subdomain disallow, noindex everything and allow user transition and testing to go forward without impacting SERPS.

Unfortunately, someone's bright idea (before I was hired) was to transition site entirely within two weeks and take down the old one right away, hence the pickle.

We understand the ramifications of large 301'ing but our current site is terrible for many reasons (grandfather/legacy issues) and our SERP visibility is good but not where we should be. That's why loss in traffic is a gamble worth taking because our new site will be 1000% improved from a SE & user perspective. Don't get me wrong, we don't take the loss likely b/c we are the 2nd largest online retailer in our market.

About 2500 top level URLs are changing.