Question about offers

So I have sent my UCAS application off and can now track my offers and I know I have 7 days to change my choices if I want but can I still change my choices if I get an offer from that uni because I was starting to think about changing on of my choices and I have got an email off that uni saying I will be getting an offer soon. Will I still be able to change that uni even if I get the offer if it is within the 7 days?