I think the V5 is already available in Australia. I think it will be available in USA in February. I have no idea when it will be available in Europe.
The point is that you have to look at the source of the information that says when it's going to be coming out. The press release from Bandai's head office in Japan said January, but didn't say where in January. Bandai USA's office have been saying February, so for USA I think it probably is February.
In Japan, Bandai will release Tamagotchis on a set date, all over the country. You can look in every toy store, the day before, but not find a new model. But on the day of the release, many stores will have them.
Outside of Japan, release dates are fuzzy. I think the stores wait until they sell out of all of the older models before bringing out the new models.