My current setup: Indigo triangle/ Indigo circle/ Red triangle:
Do I focus on 1 critter at a time?
Scene1 - Jellybeak 
I am getting on seed a Yellow and red jellybeak. According to the guide, the triangle for red and circle for yellow are correct.
Does this mean a indigo color will attract the blue jellybeak... I must just figure out the shape still?
Scene 2
I am also getting blue lollipop and sweettooth. This means the red  triangle on the right is correct to attract those 2 critter types. So to attract e.g. red and yellow lollipop and sweettooth, I would need a red candy plant, I must just find the right shape?
     

No, your shapes for the red and yellow are correct but not their colours.  As the wildlife guide states.

To attract the orange and green though you need the correct shape and the correct color (meaning you need a different color triangle and a different color round candy in order to attract the violet). You do need to figure out the shape of the 3rd candy, yes and eventually the corret color of it as well.

You will attract the red, yellow and blue versions with all colours except the correct colour. Your "code" for the Violet creature will not necessarily be the same colour in all 3 spots. The red, yellow and blue versions confirm for you that you have the correct shape in the corresponding spot but gives you (almost) no colour information. The orange, green and Indigo are what tells you something useful about colours.

I.E the colour of your plant does not matter until you find out what the "correct" colour is, by attracting the Indigo (for example) . Then if you still haven't attracted a blue, any other colour of the shape will attract the blue

thanks.... im starting to wax this candy. well starting with jellybeaks at least....

I still have my original 3 candy seeds and still have 2 tests to do. I have received 6 different candy critters from my first seeds.... can i say YAY.
Im getting the hang of this....

One question: If i get an entire plate with just pests, is it safe to say the candy plant setup is wrong, or should i put out each type of food (where i didnt get any candycritters) twice.

I'd been giving it at least ten feeds (so depends whether using single, double or super) but I've seen at least one person say a critter came for the first time at about 12 feeds in, so even ten may not be enough. I'm going to go for 15 now.

I was trying 5 feeds as well and then changed. Last night I saw how wrong that was.

So far I have had 3 different color triangles in my garden, and apparently I hadn't waited long enough to try out my berries cause just yesterday I got my first yellow candydevil (triangle , middle pot) even though I had had triangles in the middle with wild berries out twice before.

OK, thanks, safe to say then that where i got only mice, i will try new food again. and then move on to new shapes and colors!!