Taken misoprostol today, how long does it take?

Nicole
Does anyone know how long it takes? I took the 4 pessaries at 11am, took out tampon 1pm, mild cramps 3pm and spotting 4pm but nothing since? The leaflet says normally 4-6 hrs but it can take up to 72hrs to bleed but was hoping it would be quicker than that. I'm worried that it's not working? Thanks