The first stone Thanos claimed was the Power stone. It's not specifically mentioned in the movie but that stone boosts the power of all the others. So it makes sense that this was the first stone to collect.
Second, he claims the Space stone - again this makes sense as it makes it possible for him to travel anywhere virtually instantly in order to collect the rest of the Stones.
He sends the Black Order to collect the Mind stone and the Time stone from Earth while he collects the Reality stone from the Collector. Assuming all are successful in their tasks, all that is left is the Soul Stone, which Thanos needed Gamora for.
If the stone collections on Earth had gone as Thanos initially planned, then he would have been meeting the Black Order on Titan to complete the collection, however due to their failure to collect the Mind Stone, Thanos needs to go himself to Earth where he gets hold of it.
In summary I'd say the first two make sense to be collected in the order they were, but it's not so relevant for the remaining stones.