Movicol is quite gentle and a good stool softener. If you take it, it usually works in three days. The first time I took it, my intestines were on a go slow with at least a 6 day transit time. (You can do a rough test of this with a load of sweetcorn - never saw mine again

) So it took three days of once sachet three times daily. Then you should go to the loo as normal, albeit more often. Then once you have it stabilised, you reduce the movicol and work on the diet until that takes over. It may take some time.
The aim is to restore normal bowel function, and to do this, you need to retrain it by eating a good breakfast with lots of soluble fibre, chew well and drink plenty fluids. This encourages the muscular contractions (peristalsis) which start at the top of the intestine and go all the way down.
It is not a take it and go solution, and it is probably not a good idea to take a laxative until it all gets pushed out in one go. Many people with constipation problems have things like diverticules, and that is not a good way to find out

Best to tread softly.
If you are bunged up at the bottom end and need to move it, then glycerine suppositories are the way forward.

For problems at this end, the seating posture and pelvic floor release exercises are important. Google 'pelvic floor dysfuction'.
I have not had much luck with flaxseed. At the moment I am trying chia, mixed with porridge oats and dried mango and then soaked in boiling water. It absorbs a
lot 
of water and has to be seen to be believed (never eat chia without soaking. When you have seen it you will understand why). Then I put banana in it. It is ok, but not as good as the kiwi.