On the Astars without the twist grip throttle on the collective the fuel control is to the left of the collective. It's the yellow lever pointing almost straight up when in the closed position. The start/igniter button is on the top of that yellow lever.
My memory of the exact numbers is a little sketchy, and obviously you'd use a checklist right up until you go to crank the engine, but when you get to that point in the checklist it goes pretty much as follows. You begin the start by pushing the start button with the fuel control all the way off until 10% Ng. At 10% Ng advance the fuel control forward slowly until you get a light off and an increase in T4 all the while holding the starter button down. That should happen after about 1.5-2 inches of fuel control lever travel(that part is me making stuff up from memory btw). Continue to modulate the T4 by advancing or pulling back on the fuel control(my last company wanted us at 700C during the start but some prefer lower). At 45% Ng release the starter button and continue to monitor T4 and Ng while advancing the fuel control until you get to 67-70% Ng. Start is complete at that and you can get back to your checklist checking Ts and Ps and all the rest.
I find the Astar much easier to modulate during the start than the 206 but I've got a lot more time in the Astar so that might account for that. We did have one or 2 machines that liked to light off later with further fuel control travel than the rest of the fleet, which would sometimes require us to back off the fuel control slightly upon light off to prevent a hot start. An old guy with over 14 thousand hours in Astars alone showed me a little trick that worked quite well for those; Instead of holding the start button with the fuel control all the way off, advance the lever slightly(about an inch) and then hold the start button. This allowed for a much smoother start with those particular problem ships. I'm sure that is NOT an approved method though, just a little tip!