ChatGPT updated their scheduled tasks feature:

• New 'Scheduled' page in sidebar for managing all tasks
• "All tasks are faster and more reliable"
• You can schedule tasks for specific times or choose broad windows like "evening"
• 'Monitoring tasks' can search the web and check connected apps, and only notify you if something's worth reporting

It's rolling out over 2 weeks, starting yesterday. I'm not seeing it yet. But you can go directly to chatgpt.com/scheduled in the meantime.