I have recently visited Kandol lake trek. The trek is around 4-5 hours
I would suggest that you should take guide with you otherwise there is 100% chance that you will lost your trek, and you will lost in the wood and stones. There are alot of land sliding stones which will be biggest hurdle and if you will not able to follow trek you will have to put alot of effort to reach to the lake. Secondly bring rain coats; its must thing you should have while on your way to Kandol lake.
Direction to adopt for the lake:
When you will drop from your jeeps you will have to cross bridge and after crossing bridge follow trek on the right side and keep moving along with the river. After around 1 to 1.5 hours (depending upon your speed) trek you will reach to the place where you will see glacier and few waterfalls on your right side. moving little further you will see a single tree plank (do not use it for crossing river as it will be dangerous to use it as water flow is very fast and chances of fallen into river is high). You should keep moving forward on the stones and after walking little further you will find another river crossing. There you will find 2 adjacent trees which are easy to use for crossing river. When you will cross river do not start moving to your left otherwise you will lost in the stones and further the way will be very difficult and hectic. You need to return to right after crossing river and keep moving from stones. there after 5 mins walk to you find trek which will go to left. That trek is hidden in stones so be patience. And thats the only way you will be able to reach to Kandol lake by following the trek.
I would suggest that took guide with you so he will help you in tracing trek. Otherwise do not depend on the locals. They will only misguide you and you will only waste your energy in finding lake trek.