that should work theoretically, while I am not sure if you can put numbers that high into the timer control!
that is why I propsed to have it count minutes....

for gettickcount just open the API viewer copy the declaration and paste it into you project than you can use it like that:

lngTime = gettickcount 'LngTime now has the value of how many milliseconds the system is up...
now you could calculate how much time has passed since you assigne the ticks to lngTime by
(gettickcount-lgntime)/1000 'would give you the seconds that have passed for example....