Go to the revenue canada site there is a booklet that you can download. It is only somewhat helpful though as it isn't very detailed.

Anything you buy specifically for the daycare like the bookshelf is claimable and you use the depreciation chart for most furniture or major purchases. However when you sell the bookcase or stop doing daycare you also need to claim the sale amount as income.

Groceries you separate from other supplies. Even though once figured out it all gets lumped together on the same line on the tax form. Toys, craft supplies etc for the daycare are 100% unless you have your own kids that will be using them while daycare is closed and then you do a percentage. For meals you add up the number of meals being served and divide out your grocery bill. That takes care of the supper tonight and lunch tomorrow thing. It isn't as daunting as it sounds. Just keep a record for a month and use that as your guideline unless things change drastically. Remember to count family meals on the weekends. Just popping in quickly so can't go into detail right now.

Things you bought before you opened you sell to your business - for supplies use the actual cost. For things like a playpen you already had in the house you sell it to yourself as if you had bought it at a garage sale. So if you put it out for a sale and someone came to buy it put a price on it and that is what you use to claim. Just write down the items and the date the use changed to business.

Some childcare associations arrange for tax workshops if you are lucky enough to hook up with one of those that would be very helpful.