OTW
OTW has 2 meanings
Off to work
Someone who is headed to their job may use OTW to mean "off to work." Your friends, family, or SO might send you this acronym when they've G2G to work, and so CTN.
However, because people more commonly use OTW to mean "on the way," using it to mean "off to work" can be a bit confusing. If you use OTW to mean "off to work," you may want to provide a bit of context, so the person who receives your message doesn't think you're headed their way.
Example
OTW now. I'll call you on the way home
K, TTYL!
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OTW is a texting acronym typically used to let another person you are en route to where he or she is. It is similar to OMW, but not as common.
The acronym is often texted as a response to a "where are you" or "what's your ETA" type of question. It is then usually followed by a time that indicates how long it will take to arrive.