Swan 
The SEO migration plan is built on the basis of the full content; content of the new and old version. Whether it is for the redesign of a domain name or the change of a website URL, the realisation of a migration plan is fundamental. Obviously, this plan must be completed before the website goes online. The first thing to do is therefore to build the new content entirely.
Content analysis
We would advise you to keep a version of the old site, on a preprod or recipe environment, in order to simplify the work of listing old URLs. In this way, by having all the old content available, you will be able to make a comparison with the new version. It is moreover by relying on this comparison that the URL will appear. The importance of having all of the content available is essential for a successful SEO redirection to a new page. The parallelization of the two versions of content allows you not to forget redirections and, as a bonus, offers precision in the choice of each URL. Moreover, it avoids semantic distance. In short, as soon as all the new content is ready, you need to create a migration plan.
Test phase
Note that you should not get involved in this project at the last minute! The SEO redirection plan must be tested in order to check for possible errors (syntax, bugs, various omissions). Finally, it is better to take your time to make this migration a success!
SEO redirection plan with Swan
Ideally, Swan starts by testing the migration plan directly on your recipe environment. Then he deploys it on your production environment. This strategy allows you to carry out the SEO migration of your website with greater peace of mind, while saving time and money.