I have lifelong constipation. prescribed to take miralax everyday. when is the best time to take it if i want to have a movement in the morning. ?

Doesn't matter: Miralax traps water tightly & resists removal as food is digested, making your poop softer over time. You can take it once a day or space it out. It differs from stimulant meds that trigger colon contractions to aid emptying. If this is a long term problem you can help your gut by emptying at least 2X daily, if prompted or not. Use of Miralax for up to a year or more can help you end this problem