I would suggest 23 to 25 by experience to start with.
Keep yourself to 20 and save up the balance for a treat in what you crave,
In my case, it was cheese.......
I also found the Canyon Ranch cookbook a godsend - really nice flavoursome recipes and allowed you to seriously stay in the points - make sure you have plenty of mustards in stock!
I am male and followed the points down behind the missus who went for the weigh-ins. I just did it in the bathroom and plotted the results on to a graph - and remember no more than minus a kg a week - beyond this, you start to become a candidate for a gall bladder op, especially if you are over forty, fat, fair and freckled...... (sorry to be blunt).
I lost 3 stone by this method over 6 months.....
Good luck