How to train my 9 months old to drink from a cup? Or is it too early to train ?

No it isnt too early. As long as you are ready for it. By all means feel free to introduce it to your LO. Some may take it as early as 6 months wheras some may take it when they are slightly older. http://www.babycenter.com/0_sippy-cup-dos-and-donts_1439508.bc