if you look at the WHOIS the last update date is the date you accepted the push from the seller w/in dynadot, pink misfit is right you don't have to wait 7 days but you might still have a problem if the person who sold it to you had only had the name w/dynadot < 60 days, ideally you should save the WHOIS for any name asa you get it, that way if the last update date is w/in the last 60 days, ask the seller specifically whether they moved the name to the current registrar on that date, or if it was just a change in their info, as a buyer you can't tell what the change was, if the name was moved to dynadot w/in the last 60 days (it is possible the seller decided to sell quickly after moving it to a new registrar) the transfer will not be approved by the registry, so there is one way the transfer could still not be complated
it is crucial to find out all this info from the seller after examining the WHOIS, especially when buying expensive names you don't want to have at some lousy registrar, hope it goes k for you this time