Transitioning from a PhD to Postdoc. Is it acceptable to stay with the PhD advisor for 6 months to a year after graduating? My PhD advisor has offered me a postdoc position in her group with specific projects and duties post graduation. However, she has time and again advised me to do a postdoc from somewhere else as according to her, doing postdoc from PhD university is not seen in a positive sense in academia.

I on the other hand want to stay for 6 to 12 months in the same group as I have lot of additional projects to complete which would be impossible to attend to in a new environment. Also, my PhD research was in a modeling technique which was far away from my advisors expertise. And, I want to learn the new modeling technique and work in a project for which my advisor is known for. So, that way I can get the direct expertise of my advisor. 

Also, I love the city I am currently in. I am not ready to leave it for someplace else.

What do you think I should do?

(Here, I have made an assumption that I will surely be getting a good postdoc position somewhere soon).
In mathematics and in Northern Europe I have seen more than a few people do this. A grace period after graduation is not rare. But it is expected that you spend time elsewhere, preferably abroad, either employed or on long and frequent visits, or that you are very good. (Even if you are very good, there are probably other very good people seeking employment, so travelling is still a good idea.)

More importantly, going elsewhere gives you perspective:


New ways of teaching.
New fields and problems to solve and methods for solving them.
New contacts and collaborators.
If going abroad, usually a new language and a more-or-less new culture, depending on how far you go.


In most life situations, it is easier to travel now then later, even if you intend to come back. So if your situation allows, consider seeking for positions elsewhere. Current co-operators of your current research group would be especially useful, since that would probably allow you to contribute to the ongoing projects in some way, too.

Also, unless you specifically aim for it, you will never not have unfinished projects going on, though this is probably field- and personality-specific.