My recent experience

I had on-site interview last Friday, 4/23 and got the positive result yesterday, the very next working day. The result came before my following up.
Another my recent experience. On-site interview 4/15. email followed up two days later with response said they would notify me soon. I followed up again one week after the on-site interview, response said that notification would come up within two days. Within two days, email came up said I was denied.
Therefore my conculsion is people normally will notify you within a week. But if they have multiple candidates, it might take longer before you interview all the candidates.