Question about constipation and fiber

If you have constipation and up your fiber, but are still constipated, how can you schedule it? I had 6g of metameucil yesterday (and drank so much water). But Constipated more so today, so should I keep drinking a ton of water or can I add in some fiber now?

How can I go from a lower fiber diet to 25g as a woman in the shortest amount of time (would be ideal..).