I usually put it on the week before I take Tyke to get groomed (@least 48 hours before). Our groomer will put it on for us, but I hate that "stripe" it leaves on Tyke's back after putting it on! It still seems to be just as effective putting it on and then grooming, and it's the only one that really seems to help with ticks! We really have to watch for those here.
It does cover against mosquitos. I was on frontline and then switched to Advantix b/c of the mosquito coverage. So far we have been flea and tick free. You just really need to watch using Advantix if you have a cat. Advantix is poisonous to them. I have a cat and still use Advantix b/c I called Bayer (manufacturer) and they said as long as the cat doesn't groom the dog less than 12 hours after application there is no worries.