Passover, as you know, is the Feast of when the Jews left Egypt. Is there a Feast for when the Jews actually got to the Promised Land?
Not that I know of but there is Sukkot which commemorates the wandering in the desert.
When did the Jews reach the Promised Land? Joshua 4:19 says that they came up from the Jordan on the tenth day of the first month. Joshua 5:10 says that the Jews then celebrated the Passover on the evening of the fourteenth day of the first month.
The tenth day of the first month was already designated as a day of preparation for the Passover; that day each family was supposed to procure its Passover lamb. (Exodus 12:3)