[cddotdotslash]

This is a bit of a hack workaround, but all you need to do is have the function run at least every ten minutes. So, using the scheduled task feature, just kick off an event every ten minutes that invokes the function with a custom event that you can respond to instantly within the event handler (to minimize costs). Once you set that up, the function will never scale down and you'll always get hot boot times for just a few pennies extra per month.