I started giving mine a spoon when they started showing an interest in feeding themselves, like picking up cheerios and getting them in their mouths. They mostly just used it as a drumstick, banging it on the high chair tray, but eventually they started trying to get food on the spoon, then the spoon in their mouth. I honestly don't remember exact ages that they were, although I do remember that none of them were the same age when they did it. My sons were happy to let me feed them for much longer than my daughter. She was trying to hold her bottle by the time she was 4 mos. old, and was very independent through all the developmental stages.
It's one of those things they learn by themselves when ready. Mine pretty much finger fed from the time they started solids until just after their third birthdays, when I started them with small forks. Spoons are actually harder to get food on. Of course, they were supervised, and the forks seren't too Sharp, just enough to pick up soft pieces of food.