If I was a time traveler and I was texting a time traveler friend of mine, instead of texting "How RU?" to each other, we would text "When RU?"
Other useful time travel texting abbreviations:
STC - Space Time Continuum
WH - Worm Hole
GP - Grandfather Paradox
DTESDITRTS - Due to electro-static disturbances in the relative time stream...
HOS - Hitler Over Shoulder