I make the curriculum up as I go. I use magnetic letters, storybooks about letters, flashcards to help them get familiar with them,etc.
I gauge how quick to go on the children and check to see how they are absorbing by flashcard drills individually and make note of who knows what and who doesn't. I make it lowkey and fun.
I am always brainstorming on ways to reinforce basics.
I do have a workbook that I use with four year olds to help them get fine motor skills and writing practise (there are cutting activities on pages too in it)
The workbook I like is
Comprehensive Curriculum of Basic ... - Google Book Search
I don't usually start using that book until a child is about four. I only do it to prepare them for traditional school work. They seem to love using it though!