Buses are available from Gandhipuram bus stand for every one hour. You can take the bus from Kanchipuram bus stand and reach there in about one hour.
Initially, you can visit the Adhi yogi temple and spend time their for about 2 hours. Then reach at the bottom of the hills via a share auto which costs around Rs.30 Per head. Shops will be available at the bottom of the hill where you can have food and buy the things you missed to carry on.
"Always try to start the trek by night"
That's because you have to trek barefoot, yes barefoot! So it would be really difficult to trek in the daytime as the surface will be very hot. You can very well go with your shoes and slippers on if your purpose is solely trekking. 99% of the people would prefer barefoot as its considered to be a sacred place and they go on to the top of the mountain to worship God.
Things you should know before the trek-
Not even a single plastic material is allowed to carry on the mountain(except water bottle). At the bottom of the mountain, guards will thoroughly check you and even the biscuits covers are not allowed. But.. don’t worry…. they have paper bags, in which all your materials will be transferred and will be returned to you.
Buy a bamboo stick at the bottom of the hill which costs around Rs.20, which will be helpful for you while getting down from the mountain and always have a torchlight with you personally.