Since the Internet is composed of varied connection types, load time cannot ordinarily be defined. Matters are further complicated because of the possibility that any connection may stall or show erratic behavior.
For analysis, I have invented a useful formula, shown below slightly rearranged and simplified. (Units are in seconds and kilobytes.)
loadtime = 1 + (requests + KB_total) / 4;
You can measure the liveliness of your own connection with three examples.
Try plugging in your own numbers:
Every name resolution (like looking up a phone number) takes an initial effort, which I have judged as 1. Each following request consumes additional resources on both ends, regardless of data actually sent; I assign this a value of 1/4*. Finally, I assume a rather modest download speed, 4 KB/sec**. This is reasonable, as faster connections mean almost nothing to most people, and have such extreme differences, even amongst themselves.
(*The effective number of requests may have to be doubled or tripled if HTTP pipelining is disabled. **In fact, 4 KB/sec is almost twice what I get.)
The practical matter is more diffused by a comparison between load time and see time. Think of "see time" as the delay before your sight is gratified with a fair quantity of the finished document.
Better browsers provide better see times, in spite of slow connections. Caching is a tremendous help, and allows your routine internet use to be much more enjoyable. In spite of this, many web pages have design philosophies which spoil all bets.
As far as I am concerned, five seconds is a decent see time, and ten seconds a decent load time.
In course of time, this information will become out of date. You will laugh, and I can't wait.