Q: How long does it take for a manuscript to come to the Under Review stage?

You have a couple of questions. Let’s take them one by one.

How long does a manuscript take to move to the Under Review stage?

The thing is, we usually don’t provide a timeframe for these milestones. This is both because this isn’t in our purview and also because it depends on factors such as the topic and field of the manuscript, journal workloads, and availability of peer reviewers. What we can say is that as this is a Springer journal, it is likely to take a while due to the number of submissions Springer journals usually receive. Also note that Under Review means the internal team has checked the manuscript and decided to send it for peer review. This takes a while too, as there are several internal checks involved as well.

For now, you should simply keep a tab on the status update. If you don’t see a change within a month or so, you may consider writing to them seeking an update.

Does every journal follow the practice of moving a manuscript from one reviewer to another in case of a reviewer challenge or unavailability?

Quite simply, they should; otherwise, your manuscript would suffer. :-) Sometimes, you may also refer a reviewer who you know to the journal, but for this, you need to check their policy.

Hope that helps. For a greater understanding of the peer review process and journal decision-making, you may refer to the following resources:

• A journal editor's insight into what happens post manuscript submission
• Peer review process and editorial decision making at journals

All the best for the next stages!