Depends on how packed your bag is. I roast 350g and jam into a 250g bag (like a brick really ;D) - so I dont really see any movement at all until Ive emptied out the first 100g or so. Once there is some room in the bag, it puffs up pretty quickly. But Ive also found it speeds up after a few days - sometimes 4-5?
But I also wonder if there is little or no degassing after this time - could be under-roasted? Some of my earlier attempts didnt degas much - but also were quite flavourless and sour - which I now realise meant they werent roasted right through. This could certainly reduce the amount of gas being given off if they are still greenish.
So maybe taste and see :)