You are correct. The 10D was released in spring of 2003 and the D70 in spring of 2004.
My friend had a Canon D60 when I bought my Nikon D70 with 18-70 and 70-300 lenses in 2004 and I forgot the timing of the 10D release. I would have gone with Canon at the time but Canon DSLRs did not have an APS-C normal zoom until EF-S mount was introduced with the 20D later 2004.
I switched to Canon in 2014 with a 70D.
The first ef-s lens was the 18-55 in the 300d! That was in the fall of 2003! I know because I bought one - my first dslr!
The 18-55 was a "normal"zoom for the aps-c sensor size and this mount was introduced in the 300d!
At that time, Canon sort of followed an 18-month cycle for the xxD line, so most people were expecting something every 18-months. The xxxD line was about the same.
The 20d was the breakthrough xxD model in 2004. It had 5fps, nicer lcd (though 1.5"), better AF, etc. I got mine used by late 2005. I think the seller was anticipating the 30d release and wanted to dump his before it loses its value. Unfortunately, the 30d was a BIG disappointment. It was basically a 20d with a larger lcd! But there was nothing really significant came out of that.
We were hoping the 40d was better, and I was able to test it, and it had live view, with a large usable lcd! But the colors were off, especially the LCD (too much magenta), and AF in live view was impossible! It was also a tad noisy in the high iso. It had slightly better AF, basically and upped the fps a bit, but I was not happy with it, and did not upgrade. I think this was around 2007 or so. Then the 50d came out and it had much better AF, but there were some other issues that plagued it. I also didn't like the color of the jpgs coming out. This was around 2008 or so? Then the Nikon d90 came out and and it blew almost all the aps-c line of Canon in terms of performance (Low light, AF, colors, etc). From then on, Canon aps-c was in catch-up mode. I thought they were going to change in the 60d but by that time, I was no longer interested and our pro worked stop due to the need to help the family in other matters.
I think it was only the 70d and a little bit on the 7d that Canon was able to catch up. A little bit in terms of IQ and other things. OF course, many won't notice the improvements. For the masses they were just fine. I think only at the truly big jump overall was in the 750d/760d and maybe the 70d that sparked my interest again. When I was looking for dslr for my nephew Sept 2016, I was able to test this and I was surprised at the fast AF even in dim light, and the clean images at high ISO. I was stoked again!
I said, if I ever get back to pro work again, I'll get the 750d.
By 2017, we now have the 800d/77d. Even better. IF you are coming from the 750d/760d, I would not upgrade. But if you have a 20d like me, I would! Or maybe the 80d which has the same AF and most features with better build, dials, and weather sealing. This was as good as it can be unlike in the past where improvements were ho-hum. That 45-PDAF is really big in video.
But that plan was scuttled again, as I got a 5d2 with low shutter count, grip and 3 batts, etc for lower price than the 800d with kit lens (saved about U$100). It was newer sensor tech with excellent AF in the 800d or the 35FF 5d2. I chose the latter because I had 3 good 35ff lenses (a prime, a 70-200 f2.8L and a good 17-35 f2.8-4 wide). i could always buy the 800d in the future but I may not find a 5d2 with less than shutter actuations again with a grip too! Good thing too because, I won't feel bad having gotten the 5d2 with the impending 6d ii which will likely have the 45-pDAF of the a800d/77d/80d and other things as well. But I digress.
Going back to topic, that's basically the lineup of the aps-c. the ef-s lenses came out with the 18-55 as bundled kit lens for the 300d in autumn or july-aug of 2003, not with the 20d in 2004. Later on I think the ef-s 17-55 went for sale which was a big thing. I think that is just a short while after coming out with the excellent ef-s 10-22 f3.5-4.5 which I own and can vouch for its excellent optical performance!
