Is it OK to store ADA in Daedalus at this time before Shelly or after? and if so does the user has to do something before or after Shelly in terms of a swap or keep coins in exchange first?
Its always best to keep your funds in a wallet that you own.
With regards to what action you need to take post shelley, there will be documentation with the upgrade - but just remember that there isnt a deadline to upgrade Byron wallet (once shelley is live on mainnet) . So you can hold your funds in Daedalus or Yoroi wallets and just follow announcement channels or in wallet notifications, but you wont be stuck because you missed an announcement