Yes, you can change the start time or date of any plan you've purchased as long as the plan hasn't started yet. In order to change the time or date of your plan, login to your Roam Mobility account online, click on the SIM the plan is scheduled on, and click Reschedule beside the plan you'd like to modify.
You can choose the time zone you’d like your plan to operate in, so make sure you select the appropriate time zone for your destination.
You can reschedule your plan up to 6 months in the future.
Step 1: Log in to your Roam Mobility account and go to My SIMs
Step 2 - Click Details next to the SIM with the plan you want to reschedule
Step 3 - Click Reschedule next to the plan you want to reschedule
Step 4 - Select a new start date, time, and/or time zone and click Reschedule.