Being clean once again.....

ok i smoked yesterday and only took 2 hits
before that i smoked on the 29th so that was last week
before the 29th it was 17 weeks

so im perty sure i was clean before i took the 2 hits yesterday
this is my Questions.......if i smoke again today how long whould it take for me to get clean again?

i'm 180 5'8
walk 5 miles to and from work plus all the walking i do at work 4 times a week

I would say about a week since a one time high with a totally clean person stays with in the system for 3-5 days.