How can you change research advisor after contact?

[nermah1]

* I'm not sure this post fits for this forum. 

 

I'm applying to PhD program of biology field. 

 

Some of schools urge me to contact POI, because POIs might have limited RA available and limited seat in the lab for upcoming students (like me).

 

This does make sense and I understand the situation.

 

But even if you can get some information about your POI in internet, you never know how the lab environment is, or, that is, whether it really fits for me.

 

The research subject is the most important for choosing the laboratory, of course.

 

But  once I start to attend the school, I might wanna change my research advisor for any reason.

 

<That's why I want to get an admission first, then pinpoint the research advisor after experiencing one year of lab rotation. (If you rotate 3 labs for a year, then you might be sure about something)>

 

Does <this> make sense??

 

or Should I determine the research advisor through internet and phone because of available RA even before I see him in real world?

 

Or is it common to change research advisor during grad school after your decision for first advisor has been made?