When is web/mobile check-in due before departure?

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• If I did a web/mobile check-in, where do I send my check-in baggage?
• After doing a web/mobile check-in, is there a different counter to check-in the baggage?
• If a ticket is purchased from a travel agency, will you still be able to do a web/mobile check in?
• When can I start check-in on the day of my flight?
• Web/mobile check-in is not working.