Maintaining link value during site downtime

[AHartman]

We are nearly finished rebuilding a client website, but they want to have a "dark launch" period for 4 days prior to the public site launch. During that 4-day period, we will be converting their server, so they want to take down the old site and instead send users a "coming soon" message. Although we have the old site pages set up to 301 for the public launch, I'm concerned that this dark period is going to hurt the link value on the old site pages. During this 4-day period, should we be setting a 503 status code on the old site that automatically serves the "coming soon" message? Or, should all old site pages be temporarily redirected to the "coming soon" landing page? Any other recommendations are appreciated as well.

[LoganRay]

Your last idea about temporarily redirecting them would be the best way to handle this situation. 302 redirects will send the right signals to search engines, and they'll know to come back later and check on them again.