The best time to 'meet' on Sunday would be:
8am Pacific / Noon Eastern / 5pm GMT-ish
Noon Pacific / 4pm Eastern / 9pm GMT-ish
You could just open a chat room at 8am Pacific, post the URL here, and let it run all day.
try to set up a secondary chat window immediately
try the Sunday window for a few weeks and then decide about a secondary window
consider your options carefully and select those which are most relevant to you:
weight loss is hard. let's go shopping!
exercise is hard. let's go shopping!
shopping is hard. let's tick boxes!