It can be done in 2 weeks but normally takes longer. There is no real timescale as all dogs and situations are different.
He needs to be watched like a hawk when indoors as you need to correct the behaviour straight away and take him outside. Don't use harsh tactics as they may result in him hiding to pee.

It can get frustrating but they will eventually get the idea.
I would allow about 8 weeks before changing tactics

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