Will be flying on a AA coded flight next week and intend to credit this to AY.

Under 3.3 of Finnair Rules, it says "Finnair Plus points can be collected only after membership begins". I am assuming it will be alright if I sign up as an AY member the day before my flight?

See that aa.com allows me to add my AY membership number under passenger info. Do I still need to give the agent my AY number again when I check in for my flight?