Content is the hardest part of a digital transformation.
While we're enthusiastic about ditching old design, many stakeholders want to hang onto irrelevant content for grim death.
If you have a mature content strategy process you'll already be managing reviews as part of the content life cycle. If you don't, your stakeholders are likely to be more attached to the existing content.
Breaking this attachment is the key to a successful content transformation. That's done by focusing on meeting clearly defined goals using a clearly defined process.
It's also important to set the scope: existing content only. You're not trying to fill any gaps, although you will identify them.
You should start your transformation as soon as you can. Get ahead of any website redevelopment, so you give yourself the maximum amount of time.
But before you start, you need to get stakeholders on board and have an up-to-date content strategy.