I created the following example to understand the instances in python
import time;
class test:
mytime = time.time();
def __init__(self):
#self
the mytime = time.time() is executed when the class is defined(when the interpreter runs the class-definition-code, and this will be run only once, so all instances will get the same mytime.
if you want different mytime in different instances, you have to use the self's one, and access it with instance name rather than class name.