Ken Wade asks:
"is there a way of determining what page a Google search first appears on without manually searching [through all the search results pages]?"

Not that I know of specifically, but I don't worry so much if a page appears beyond about 100. This is because, in the higher numbers, a huge jump can take place in a short space of time. For example, a page could appear on Page 231 on one day and drop to Page 79 in a few weeks, simply because a few good inbound links were added to the web for that page and Google gave the page a slightly better ranking for that change.

Still, if you really want to track the exact page number your web page appears on, start where you found it last time and work backwards. (This assumes you are making positive progress week to week). In other words, if you found it on page 121 of search results last week, start searching on page 121 this week, then page 120, 119, etc., until you find it.

It's more difficult to go from let's say Page 4 to Page 2.
That is because there is usually more competition in the lower page numbers as companies who put a modicum of effort into SEO can probably appear in the top ten pages easily enough. To get to Page 2 means that you are probably competing with people who are putting serious effort into the search engine optimization efforts.

So, consider any valid number up to 100, or maybe even only 40 or 50. That way, when you chart your progress, the scale of your chart (0 to 50) allows you to see movements in the single digits.