When to propagate my Aeoniums

Magical Meerkat

Hello,

Here are two of my Aeonium which are getting tall and don't look like they are going to branch on their own. I want to propagate them so they branch and I've watched a video, but it doesn't say when is the best time of year to do it?

Any ideas?

Ps the photos were taken last Sept. They are currently indoors waiting for warmer weather!