If you drive by the shift arrow you'll find yourself shifting in the 1500-1700 rpm range. BTW I actually do mind that suggestion and my mileage tattletail is currently showing 33.6 mpg with an average speed of 28 mph. Yeah, it's all city driving and I've gone so far as to choose my route so that stops are minimized.
Now concerning downshifting for accelerating, that depends on how fast you want to accelerate. These are small engines and even with a turbo they are lacking in torque and power below 2000 rpm. If you need brisk acceleration you should downshift so you are seeing about 3000 rpm's, if you need to really accelerate then downshift so you see about 5000 rpms.
Note, as a newbie you may not be aware that you can skip gears shifting up or down. Plain and simple you can skip gears without doing any harm at all to the transmission. Just be aware that if you try and go from first to fifth you can harm the engine by lugging it. Lugging is basically applying a high throttle setting when the engine is turning less than 1200 rpm. Now one example when a skip shift makes good sense is when you see a red light runner coming straight at you. In this situation slamming from fifth to second while going full throttle at the same time can have your car basically jumping out of the way of that red light runner. Done right the power hit will be just a bit insane and you WILL get a strong hit of torque steer, just hold the wheel straight and stay in that throttle. Because the car will reign in that torque steer and getting clear of that idiot will likely require every bit of that power hit.
It's one thing that took me a whle to learn, the way the torque steer correction in the car works requires a moment of two before it kicks in. If you start jerking the steering wheel you can get into a positive feedback cycle that can have you weaving like a maniac. DO NOT FIGHT THE TORQUE STEER, let the car do that. What you have to do is simply hold the steering wheel steady. BTW, second gear is the worst gear for this because it's the gear where this car really shines in acceleration.
For me, second is the Fun Switch. That 1969 350 hp Corvette next to you at the light doesn't know you'll humiliate him up to 60, so give it a good pull in first and then hit the Fun Switch and that Corvette driver will be thinking WTF, some damned Roller Skate just blew my doors off. BTW, after you hit 60, HP rules the day but a lot of fun can be had if you keep it under 60.