We know that the CP arc/gauge increases in value the higher your trainer level. We know you can find higher CP pokemon the higher your trainer level. We know that catching a pokemon and transferring it gives a set amount of candies.... so....

I say use the early levels, maybe until level 10 or higher to only catch pokemon... this way once you are higher levels and can catch CP 600 pokemon you have enough candies for evolution/training.

Even though the CP gauge is relative to your trainer level, the pokemon you caught at level 3 won't increase in CP when your trainer level goes up. It will just increase that pokemon CP cap. Ratata CP cap will go from 80 to 120 for example.

In other words catching a Pidgey at level 3 with 25 CP and training it or evolving it is pointless when you can catch it a few levels later at a higher CP and use less candies for training/evolving.

Example: using random numbers.. it doesn't matter what the cap is. A cap is a cap.

Trainer level 4 CP cap 150 Pidgey at CP 25 caught when you were level 2 Pidgey at CP 70 caught when you were level 4

Why bother training the original Pidgey... they can both only go to CP 150 while you are level 4... it's pointless. Hence wait until you are higher leveled to bother with training.

If I'm wrong PLEASE call me out...