I am wondering if those research articles published by a journal before it is Scopus Indexed be also Scopus indexed. I am referring, for instance, to those research articles published in the journal's first three volumes.
Genesis Naparan , in my opinion, they should not be considered if the publication is a year earlier, you can check the journal profile on the Scimago website, it provides a clear track of the journal since its introduction in Scopus.
Interesting question Genesis Naparan because I too observe that for some journals that can be the case... but not for others. Can't seem to find out the hard and fast rule of Scopus' selection process.