As I recall I got the same advice. I did intro and helitrox with a naui tech instructor. Before that I had over 100 dives in my drysuit. Somewhere around number 75 of those and 200 or so overall I got my first set of doubles. LP72's. Put 30 or so dives on those and then bought a set of lp 85's. Then I started tech classes. By that time my buoyancy and trim were good in the drysuit. Very good in fact and I saw no noticeable issues of any consequence when I switched from singles. I started sidemount after diving doubles for nearly 6 years. Somewhere around dive 550 or so. I now have over 100 in sidemount wet and dry. Taking my time has paid off every step of the way. I was in a rush in 2007-8 when I started tech. Plan was to do the Doria when I turned 50 in 2010. Then my wife died. Still haven't done the dive but it's not that important any more. I get excited on a 3 hour sm dive in 20 feet of water looking for bottles. I am far enough in my training now to do any dive I really want to do. I'm ok to 200 feet. That's good enough for now. Tech diving is expensive. The risks are high. If you don't have the basics like buoyancy and trim nailed down in what you plan to use to start, you shouldn't even start tech training. IMO. I turned down an an/dp student earlier this year. He had over 100 dives and numerous recreational certs. Most of his dives were class dives. I talked him into getting another 100 or so fun dives in. If he was still interested in tech after 50 of them he should buy a set of 72's or 85's and take intro with me or someone else that knows what they are doing. Get 50 dives in them. Then talk to me about an/dp.