It is great that you think about timing.
To be honest you should not focus on case timing. During the interview, partners may stop you in a middle of a case without any recommendations. You should be prepared for that.
What is more, you should be the guy, who I can bring to a client interview - that's all MBB want from a candidate. At the same time you should
- Structure in MECE way
- Drive hypothesis
- Be proactive
- Have a matured communication (eye contact, use hands)
- Calculate fast and without any mistakes
All the best,