You probably won't be able to do this but, a really good way to gauge if a unsocialized, recently gelded horse is to put him in with a mini.
And, take the bottom fence rail off in one part of the paddock (adjacent to another paddock) so the mini can get out of the paddock if the larger horse gets aggressive.
Realizing that will be difficult for you to do, if you have side by side paddocks, I would let them get used to each other from either side of the fence for a few weeks and keep an eye on them. And perhaps, after that, start hand walking him with another person and horse. I would really take your time though - some later geldings just never get the memo that they are not a stallion anymore.
I'd also make sure that you wait a couple more weeks if you are going to put the gelding out with a mare. If he was gelded at the end of March, I'd wait until into May to be safe.