You're asking something that nobody can truly answer. Chances are that you'll be able to order the phone tomorrow and you'll get it by the 19th but conversely, its possible that by tomorrow you'll be so far back in the virtual line that you'll not get it by the 19th.
The last time I checked (last night) apple was still advertising the fact if you buy it online you'll get it by the 19th. when (or if) that changes is anybodies guess.