When I first started pumping, I used to have 1 real let down after about 15 seconds of pumping. Sometimes I would have a second letdown that lasted only like 10 seconds (maybe around minute 10).
Now, I have been pumping exclusively for over 4 weeks. I noticed I now have 3 letdowns! One right away that lasts about 5 minutes, one around minute 7-10, and one around minute 15-18. The second two letdowns are not nearly as long as the first, but last about a minute. I used to poo poo pumping for 20 minutes, but not anymore!
How many let downs do you have?