I'm with Jacquel... See if your local school district has a list of skills your child should have before entering Kindergarten. And once you've gotten them through those skills, see what the standards are for finishing Kindergarten - never too early to give them a head start
Also, the biggest bit of advice I can give you is to make yourself a routine and stick to it. Kids love love love routines. If I do the calendar instead of the head teacher and do a few steps out of order, the kids catch me right away and have me do it the usual way. And don't forget to schedule lots of playtime! I know money is tight but some kind of social activity like a playgroup or tumbling class can help them with the big social adjustment of school. Make sure too to include some kind of PE every day too, having a game to play outside or whatever, get them started early on a healthy lifestyle. I'm sure it wouldn't hurt for you to get out and get active with them too! Nature walks can be a lot of fun too, get a leaf book and you can learn the names of all the trees around you.