In my personal experience I work on £100 monthly business every canvassing shift:2-4 hrs.
As others have said it does depend on many different variables but this will give you a realistic guideline.
Somedays you will do much better and other days will be crap....thats just the way it goes.
Canvass weekends and evenings,they are always good for us.You will always pick business up in the day but because more people are out you may work longer...better to work smart
Just decide youre gonna do it daily and set yourself daily and weekly goals,this helps keeps you on track when you get distracted, like your mates coming round with the beer
Good luck...its well worth the effort.In 6 months if you work hard you ll be stylin.