Open grouped tabs, closed up upon opening browser ?

[Slake]

I have 100s of tabs all nearly put in groups, but every time I load the browser all tabs are opened, meaning I have to click on each group name to close them up. I have multiple windows with approx 10 groups per window with 10s of tabs within each group. So each time it takes a while to close all groups up. Is there any way to start the browser with the grouped tabs closed ? Thanks !!