If you have a campaign world/city/town which you've worked out in advance, you should be able to prepare a sheet or two of background info about major religions, a map of the general area showing major towns, that sort of stuff. Give this out while they are rolling up characters. It's something for the fast ones to read while they wait about :)
My favourite way of beginning an adventure is in jail - the party have all been arrested in a riot/bar brawl. They may not have been involved, but the watch just grabbed the nearest half dozen citizens and locked them up.
They can then be offered the standard approach by an influential stranger who can get them off the hook IF they perform this leetle service for them...
Unless your players have played in your world before, it isn't a bad idea to have an adventure which demands they travel right outside their own area, so you don't have to go into huge detail about their previous life history. Ideally you want an adventure which takes place somewhere NONE of the characters will ever have been before.
As for background, any players who don't want to work out great detailed backgrounds of their own can be told 'You are a dwarf from the mountains in the north'/'You ran away from your farming home and became a thief, because you didn't like your stepfather' etc. If the player doesn't actively seek a detailed background, they will be happy with a minimal excuse for existing.
Those who do want a detailed background are capable of inventing their own as a rule. They will say things like 'Are there villages in the hills, I think my character lived on the edge of the wilderness learning to track and hunt' To which you reply 'Uh, yeah, there's a village called Hillfort that would do well. I expect your character hunted bighorn sheep, maybe wolves in the winter, that sort of thing. There will have been orc raids to deal with too...but only once every few years.' Then make a squiggle on the map for the player's village (which you just invented).