I'm not completely clear of what you are asking, but you shouldn't use a timer IMO. There is no reason to tell mIRC to wait to keep using the WRITE function. A WHILE loop would work better.
ON $*:TEXT:/^!subluck\s\d+/iS:#: {
subluck $2
}
alias subluck {
VAR %x = $1
VAR %y = 1
WHILE (%x >= %y) {
WRITE Giveaway.txt $nick
INC %y
}
}
The above should give you a basic idea of how to implement it. In the above example, if a user types "!subluck 5" then it will write their name to Giveaway.txt five times.