Agree with Beety, let her enjoy playing with instruments but don't even think about proper lessons, she's too little.
We're lucky to live near a music centre that offers lots of things but particularly Ragamuffins classes on a Saturday morning. They don't 'learn' an instrument, it's all play, but they do bash a few bongos, hit triangles, etc. etc. etc. And without pushing anything, they help children discover rhythm, fast/slow, loud/quiet.
I think ds was about three when they started talking about Quinny Quaver and Chrissy Crotchet (I know it sounds vile but this is age-appropriate). A very clever 'curriculum' that allows them to explore music for fun but in a way that will prepare them for learning an instrument when they are older.
Google Monkey Music or Ragamuffins and see if there are any classes near you on a Saturday. Ds loves it! (And I am not musical at all, fell into it because took ds along to a toddler sing a long, hadn't realised it was actually leading to anything.)