When i start to type a message, my S8+ almost always puts a space in front of the first word and deleting that space every time is irritating. It started happening with my old S7 after an update a couple of months ago. I was really hoping it wouldn't happen with the new phone.
Doc1224, we want you to have the best experience possible on that device. Are you using the text messaging feature on the phone? Did you download a 3rd party messaging application?
It sounds as if you have an automatic signature for your messages set up which is just a space and you are starting your message after the signature. Check to see if you have an auto signature for your messages and if it is only a space, delete it.
I tried creating just such a signature in my messaging app and the exact same thing you are describing happened.