The last record didn't make the spreadsheet and graph... Finished yesterday.

Here is the graph (I've removed a data set for cable, as ADSL is the major factor here anyway)

You can see definite spikes in peak times, and it seems best from 8am till midday.

But - this is only one sample and one file at one (shared) server, so this graph may or may not apply to you.

Hope this gives even the most tiniest little bit of an insight into speeds (though it will definitely change over time)