In the North East, the sun sets early as compared to the western parts of India. So you get lesser hours of daylight to ride unless you start early in the morning.
Another thing to keep in mind is the times at which the check posts close. If you show up late at one of these check posts, the police may ask you to turn back and come again the next day.
This is very important as it could mess with your itinerary. It may help to have a local person take a look at your itinerary to point out any issues with it.
Our entire Nathula leg of the ride could have got ruined. We reached the check post two hours late. Six tourist vehicles had already been asked to turn back. But thanks to the intervention of Karma Tenzing and the fact that we were the guests of the Commanding Office at Nathula, we were allowed to pass as an exception.
Planning is key in such places. You really can’t show up and figure things out as they happen. Unless you have all the time and patience in the world. 🙂