I purchased three dutch iris bulbs but only have one pot to plant them in. To get this highest chance of something coming through should i just plant one of the bulbs and discard the other two or should I put all three in the pot and update the pot later?
If your Dutch Iris bulbs look like small pointed onions, they should be planted 4 inches deep and 2-3 inches apart - unless your pot is very small, in which case it's probably not deep enough for even one bulb, you can fit all three into it. Plant with the pointed end upwards, water in, and stand the pot in a sunny area. This answer assumes you're not talking about Iris rhizomes for bearded irises.
If the pot you have isn't deep enough, don't plant, just go and buy a bigger pot, then plant.