I believe there is a certain amount (weekly) that you are permitted to earn before it affects your benefits while on mat leave. You should be able to find that on a government website. In terms of income earned, if you open as a sole proprietorship, you will need to declare the income regardless of whether you take any drawings. Only if you are planning to incorporate would you be able to defer drawings. I can't see any benefit in creating a corporation unless you plan to open a centre. Your home insurance would probably not cover a daycare if it is a corporation, and you are looking at a minimum of $1000 in legal fees, and that much per year for accounting.
You can have your income entered as either the cash or accrual basis, and if you use the accrual basis, the deposit would not be counted at this time, but would be deferred earnings to be used for the client's last two weeks or last month, so you would be okay. If you enter income as received, however, (cash basis) you would need to declare it now. I'm sure it is worth setting up an appointment with an accountant to have them advise you on how to set everything up in the best way for your situation.