I'd say the opposite actually - stick to capitals! Easier to write if she wants to write young.
However, you will find with subsequent siblings that there is no way of censoring what they get first, or second or whatever in terms of introduction to reading. Children don't learn in a linear way, they learn in a higgeldy-piggeldy way, but somehow it all comes together when they're ready. Mine have all learnt letter names first, with sounds added in when it's been relevant to helping them to learn. None of them learnt phonics first. DD1 learnt to read on her own aged 5 and, now 7, is an avid reader; DD2 (5.5)) is slower than her sister, but is at the stage they would expect her to be in at school. DD3 (3.5) is beginning to learn her letter names and is already starting to match upper case to lower case. They don't get confused, or if they do, it doesn't matter - they'll get it eventually.
Get hold of 'Read With Me: An Apprenticeship Approach To Reading' by Liz Waterland for a really, really good understanding of how children actually acquire the skills to read - in what order etc. And 'Games for Reading' by Peggy Kaye is great for ideas.
One of those foam mat alphabet sets is a great resources for games; and fridge magnets. Just immerse her in a world of letters and words and keep telling her what they are and/or what they sound like and she'll learn it.
Matching games; and spot the difference are also good for learning to read; sorting things. Anything that gives them practice at looking carefully at things to identify them. Later on, a nice game to make is loads of two letter words stuck down on a file folder, with the same words printed onto card, and to match them up. My DD3 (3.5) likes a game I made like this for her big sisters, which is meant to be like bingo, but she just matches the words - four and five letter words. She's not reading them, but she's having to pay close attention to them - each card has 6 rhyming words on, so they all look similar.