You don't need the building before anything else but you do need the building before you will get your license as the facilities are a big part of the inspection.

Get the regulations for your province first. Understand what is required of you as a day care operator (qualifications, experience) and what any building is also required to have. Then do your research in terms of demand in locations before finding a suitable property. Would suck to end up with a property that doesn't meet your local requirements from a day care and can't be renovated to bring it up to code, would also suck to have the perfect building in a low demand area.

I think one of the reasons not many places take in very young children is lack of demand. Remember, most parents take up to a year off and so, most parents don't require day care until their child is 12 months and they return to work. Sure, some parents want to/need to return to work sooner, but again, you'd have to research what makes parents return to work sooner and how many in your area actually do it.

Do they go back Full-time or part-time? Do they leave their baby with grandparents since the child is so young? Do the parents try and work 4 12-hour shifts vs 5 standard shifts meaning they need extended hours of care?