My friend went for stamping yesterday he spent 14 hrs inside before getting stamped at niagara.
Before that, his sent back three times as he didnt make between 8am-8:15 am either on tuesday or thursday.
Somehow he got through yesterday but 14 hrs at one place just for 15 mins work - if you think you can manage then goto Niagara
Else goto Kingston which is open 24/7 and in 15-20 mins you will done.