Personnally I do not trust /timer to evaluate huge amount of seconds

I would go this way:

alias starttimerlist timer 00:00 1 1 starttimer

alias -l starttimer {
timer 1 120 starttimerlist
timerlist
}

alias -l timerlist {
timer 7:30 1 1 /msg #options 4Stock & Option Market Open "Good Luck Fellow Traders"
timer 13:45 1 1 /msg #options 4Last 15 mins of Trading
timer 14:00 1 1 /msg #options 4Stock Market Closed "Afterhour Trading In Effect"
timer 14:02 1 1 /msg #options 4Equity Option Market Closed
timer 14:15 1 1 /msg #options 4Globex Market Closed
timer 18:00 1 1 /msg #options 2After Hour Trading 4"Closed"
}

To start the process:
/starttimerlist