Around the house doesn't replicate skiing, but does help the feet feel more comfortable in confined spaces. As I surf all year round and avoid shoes as much as possible, getting used to ski boots does usually take a couple of days.
Don't know about Argentina so you may wish to get the boots adjusted before you head off. Just a couple of things to note as well, make sure you are wearing ski specific socks, i.e. thin woolen socks. Circulation is more important than thick socks for keeping your feet warm. Also, if you have put on any weight since your boots were fitted, that will also affect their fit (5kgs extra and my boots are tight as).
If you are in Australia, there are some good boot fitters in Brisbane, Sydney and Melbourne (don't know about the rest of the majot cities) where you could get the work done. Let me know where you are or post at ski.com.au.