I know it is supposed to start tomorrow, just need to know if I need to waterproof everything today ?

thanks

Yes, absolutely you do.

Chaing Mai , are you sure about today ? I know tomorrow is a def

You're funny, do you think you'll get a different answer if you ask the same question again!

Here, read this, they started throwing water in Chiang Mai yesterday: http://www.thaivisa.com/forum/topic/717917-its-begun-wet-today/

I only asked for clarification because I know that different cities have very different dates for Songkran, Pattaya for instance has 10 days ! But I read that Bangkok has only 3 starting from tomorrow, apologies if you thought I was dismissing your answer. :-)

You should plan for random, rather than wholesale, acts of wetness today.

Looking down from the passing BTS train, it looked fairly wet on Soi 4 at ~ 12 Noon.