Answer depends on the yeast (liquid, dry), yeast condition or age, ale strain used, and amount pitched, and temperatures of wort at pitch and since all affect yeast growth. If cold, the yeast could just drop right out of suspension, or if hot, you could have killed them. Neither will ferment....but, I have also underpitched to a cool wort that never looked like it was fermenting, but did, and I had ones go so fast that I never saw it fermenting (but there was the telltale signs of fermentation having happened in the form of a yeast ring).
The fact that you poured your beer through a strainer indicates at least a minimum amount of oxygenation was happening, and a little shake of your beer to rouse the yeast and introduce some oxygen might help right away.
If you haven't seen something change (even slightly)or start to happen by this afternoon (presumably two full days and a little shake), you may decide to repitch with a yeast that matches your style and ambient temp of ferment.