I had kids that slept a lot too....I gave the dose first thing in the AM,  either before or after nap,  depending on the nap time (usually after) and then at bedtime,  my kids went to bed at 7:00 for years.  They both did fine on this schedule.  The only time I wake my kids up is if they are sick,  I then dose in the middle of the night, an extra dose, and give them a sweet drink.  Both of my boys due to illness had hypoglycimic issues when they were little,  they are 6 and 9 now abnd are doing great.

Good luck to you.