The four shrines open with the mountains, not the calendar. Gates are usually unlocked around Akshaya Tritiya and close by Diwali, which leaves a working window of roughly six months.

Allow more days than the itinerary suggests

Ten to twelve days is comfortable for all four. Anything shorter means driving long hill sections back to back and arriving at each darshan already tired. Altitude deserves respect above Kedarnath in particular.

Where to break the journey

Uttarkashi and Barkot are the natural halts on the western half, and a night in Uttarkashi before Gangotri is worth planning for. Monsoon weeks in July and August bring landslides; if you can choose, travel in May, June, September or October.