Everything depends on company policy (see Subway thread for example)
BC Labour Ministry take:
Overtime
Daily overtime pay is time-and-a-half after eight hours worked in a day and double time after 12 hours worked in a day.
Weekly overtime is time-and-a-half after 40 hours worked in a week. Only the first eight hours worked in a day count towards weekly overtime.
Factsheet:
Hours of Work and Overtime 
Averaging Agreements
An employer and an employee can agree to average scheduled work hours over a period of one, two, three, four weeks. Averaging agreements must be in writing, and have a start date and an end date. Overtime is payable:
- After eight hours in a day if extra hours have been added to an employee’s schedule, or
- If the employee works more than an average of 40 hours in a week over the averaging period (e.g., 80 hours over two weeks, 120 hours over three weeks.)
See:
Averaging Agreements
source:
Government of B.C., Ministry of Labour, Employment Standards Branch, A Guide to B.C. Employment Standards
Most small business will just do straight time for anything less than 40hrs a week. the 41hour is OT at 1.5. Again - this is for most small business. Large corporations will do 1hr of OT IF the employee works 9hrs in a day, but still stays within the 40hr threshold within the week.