My suggestion is 9-12 months as it usually takes 6-9 months for sustained behavior change, and then another 3-6 months for others to perceive that change. Most of my clients that start at 6 months end extending to 9-12 months.

I typically meet virtual on video as I find it very effective, provides much better scheduling flexibility, and clients often prefer to schedule our sessions on days that they are working from home. If the person is in the Silicon Valley area, I do find it useful to meet in-person for the first time to establish the connection.