Nonook,
Don't think I rate as a mathematical genius, but POT is simply the ratio of your profit compared with how much you have bet to get that profit, usually expressed as a percentage.
Example - you have wagered a total of $100 in bets and you have returned $120. Your profit is $20 on an outlay of $100. 20 divided by 100 = 0.2, multiply by 100 to get percentage = 20%. You POT is 20%

HTH.

Kenchar is correct, an answer to your specific question is not possible in the way you've asked it. If your POT was 1% you would need to turn over $100,000 /week to get your $1000 profit. If your POT was 20% you would need to turnover $5000 / week to get your $1000 profit.