You know in chemistry you don't just dump the ingredients into a beaker and shake. They have to go in the right order *and* just as importantly be combined at the right rate. A society is no different. Nobody is arguing about when the tag "immigrant" can be applied. They are arguing about how fast immigrants can be integrated into the existing society. Only a fool would argue that there should be no limits or that there is no difference between someone who has been here 5 months and someone who has been here 10 years.
Stop being so PC and actually think about the problem. Come visit Vancouver and see what too rapid immigration has done to rents and property prices.