Me. I used very early, about 2 weeks i think. that time I could only pump 60ml. Later getting more and more. Yes, tiring but later I got used to it. Anyway, it's a good pump at a good price.
I use Avent Maunal Pump too, it is really good. I used it the night before, one week after giving birth, I can pump 150ml within 15 minutes. But it is a little bit tiring.