I'd start with a good handful of them. Wait and see how fast they travel, maybe take another handful tomorrow, depending on how regular you normally are.

You can also get some fruit paste stuff from chemist to get things going, that's what I normally go for when iron supplements back me up and I feel like I am going to crap myself a new one, happens a lot sadly.
I find fruit based stuff works for me better than anything else you can get to move things along.

..Laura