If somebody has the opportunity to move into a new residence during the period of Sefirat Ha’omer, he is allowed to do so, and he does not have to delay the move until after Lag Ba’omer. It is also permissible to paint, plaster and wallpaper the new home before he moves in. Furthermore, one who moves into a new residence may host the traditional Hanukat Ha’bayit celebration during the Omer period. Words of Torah should be spoken at the event so that the festivity will have the status of a "Se’udat Misva" (a "Misva meal"). When one moves into a new residence in Eretz Yisrael, the Hanukat Ha’bayit celebration in any event has the status of a Se’udat Misva, as establishing residence in the Land of Israel is itself a Misva. But even in the Diaspora, a Hanukat Ha’bayit celebration attains the status of a "Se’udat Misva" if words of Torah are spoken during the event, and it thereby becomes permissible during the Omer period.
(Based on Yalkut Yosef, p. 80, Halacha 25)
