%@ is the specifier for timestamps in output formatting:

/fset send_public %@%P<%n$2%P>%n $3-
/fset send_action %@%K* %W$1 %n$3-

If you've logged on and there's a stale connection still up holding your nick, you can notify the server that it's a ghost and get it back with the following:

/m nickserv ghost <nick> <password>