In what time a backlink takes effect (in SERPs)?

It'll be a while. Instead of waiting around for it to show, spend that time finding more great links

 

Nobody knows the exact time because Google work mysteriously.

 

i noticed first changes after maybe 2-3 days and major effect after 7-8 days...
(however i never got any pr7+ link)
but all depends how big is rate of crawling of site where link is places...

 

it all depends on how often the page with the link is updated/cached by google. if it is on a page that is cached daily, then less than 48 hours. if it is on a page that gets updated every week or so, then add 48 hours to it. I have a link on a high PR5 site, but the entire website has not had any changes to it for months, and google does not visit it very often.

 

i added a contact page to my site, it took 3 week for google to pick it up

 

I've followed this on one of my sites... And it took 3 days.

 

everyone is right about it taking a long time. i say don't waste time checking on the backlinks just set a schedule and follow it and worry about continually building them. "If you build they will come"