It's a bit like asking 'how long would a 1 megabyte file take to download via the internet?' - As we all know there are many variables and the best answer would be to try and see. In this instance we have a range of times ranging from the worst case to the best case. The best case is based on the slowest link (our dialup probably) and some overhead for the TCP transport. The worst case is probably unbounded as we all know how slow the internet can get. So 'qualify and quantify' and where you can't quantify - test or make an educated guess.

'How long is a piece of string??'
'How Long is a chinaman'