when to start using a non lidded cup

[kbaby]

can anyone help at what age should they be able to drink from one without throwing it down themselves.

my dd (2.5) has always had one, she has been trustworthy with one alone since about 15 mths, but she only has water in it so my furniture and carpet is safe

As soon as they can hold a cup, drink from it and place it back on the table... my dds never had those lidded things, I could never get to grips with the lids! Water only here too...less stains when it does tip!