I don't know about Canadian law, but in US, one of the first orders of business is to file a Fictitious Name application with the State Secretary of State.
Then file SS-4 for EIN (Employer Identification Number).
Local laws may also require a city business license.
IRS - sole proprietorship; partnership, C-corp; Sub-S election.
Payroll taxes; Unemployment Comp tax, Workman's Comp, etc...
If income (& expenses) expected quickly, those are items to definitively look into.
Also - separate business bank account. Don't co-mingle business & personal funds... when in doubt, they are personal expenses, but can always put in for reimbursement from company.