Why first time string doesn't come properly?

[Jerson]

Do a dummy serout in your initialization routine before you start reading/writing to the screen
Simply DEBUG 0 should do it. I've seen this issue covered earlier, so, it may help to search here. This happens because the DEBUG port is not initialized till first used by DEBUG.

[Ioannis]

Set the port to HIGH state prior every serial command. Even better before TRIS command.

That is a good practice, to set the outputs before TRIS commands,so you have no glitches at the outputs.

Ioannis