Yep that be a flea. Ugh.

You asked how long it will take. That depends on what you used. Here, refer to this chart: http://www.drsfostersmith.com/pic/article.cfm?aid=325

As you will see, some products kill adult fleas, some also kill the larvae. Some stop reproduction others do not.

BTW, keep an eye out for a few hours in case any of the pets has a reaction to the product. Oh, and be sure what you apply on a cat is FOR a cat; many of the dog formulas are toxic to cats, and vice versa.

Here is another chart: http://www.veterinarypartner.com/Content.plx?P=A&A=545