Our article about the combined pill, Combined Oral Contraceptives (The Pill)
, says "If you don't take it at exactly the same time -- but still take it on the day you're supposed to -- that won't make your pills ineffective: it's just a safer bet to take it around the same time to keep you in the habit to reduce the risk of you spacing out a pill on any given day...If you want to be as close as you can to a perfect-use effectiveness rate, you'll want to try and take your pills within the same three-hour window each day."
So it sounds like you can pretty much start taking your Yasmin (which, yes, is a combined pill) at whatever time works for you the next day you need to take it! If you want to be really careful, you can do that by taking the pill within three hours of whatever time you took it the previous day. For example, if you take a pill at 3 pm, but want to change it to the morning, you could take one the next day at 1 pm, the next day's at 11 am, and the next day's at 9 am. It'll take a few days, but you'll get there!
Does that answer your question?