Not sure you will ever get smoothness you ask for. Do you realize that event fires for every keystroke? So if I want to add "new" to the end, it has just run 3x. I guess it all depends on what the called code is doing. Are you sure you would not be better off with some other event, such as AfterUpdate? Regardless, if you are asking how to get the cursor to the end of the entry, you need to get the length of it's Text property after setting focus, then set the SelStart property to that number.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.