Flowering straight from seed?

I'm a complete newbie to growing, but I've done quite a bit of reading and I've read articles/threads/journals where people have been able to start flowering straight from the seedling stage (maybe a week vegging or so) and my main question is this possible and how would I do it? I just want a little weed to share with friends and smoke myself, quality isn't really a big issue either.

Use an auto strain?

I've only got random seeds that I got off of a friend

It's possible the plant will grow for about 6 weeks and then start flowering, maybe sooner. You may not get much yield though.

I'd do a Sog style grow. Lots of seeds in small containers to use all the light available and just start with 12/12. You'll get lots of little cute dwarfs

No plant will flower after a week from seed. Auto's flower after a few weeks of veg or so.

Done both, the auto I grew (sweet tooth) started to flower after 3-4 week`s with 18 hrs of light when I grew reg. seeds with 12/12 from seed they did also take about 4 week`s to show sex and as some already wrote, you get some cute dwarfs, I guess yield was about the same, one nice main Bud that came in around 10g and another 10-20g of smaller and more flimsy Bud`s

but surly a option if your in a hurry or just got lots of free seed`s, as you will get a lot more out of a plant`s potential if you let it mature first, but agin if you have seed`s for it and maybe even like to keep em small (is a plus for any artificial light source) it could be a way, in the end the outcome might be the same, etc 4 mature plants that each yield 60g or 12 small once that each yield 20g different is time and size of pot`s and grow style/technique