We don't normally plan trips that far ahead, but we have visited Siem Reap every month so far this year and it is highly likely there will be a trip in May. If we have 3/4 or more people wanting to go at a specific time we try and mould a tour around them. We can arrange private tours for any number of people, but less than 6 works out more expensive, as transport costs are the same.
Be happy to see you and your friends Somnat.