1. Question: Why does the Shulchan Aruch (Orach Chaim 426:2) hold we should wait until Shabbos to say Kiddush Levana in order to beautify the mitzvah but one should not wait to get his tallis if he only has his tefillin even though wearing the tefillin with the tallis beautifies the mitzvah?
A. There is a debate whether you should do a mitzvah sooner than later without pushing it off or if you delay and you do it in a better way than it is worth pushing it off. The Mishna Berura (25:1:7) by this tefillin case says a mitzvah done in a timely fashion is more beloved.
B. The reason to push off saying Kiddush Levana from the earliest possible moment, assuming you will have a good chance to do it later, is to say it while feeling fresh and nicely clothed.
Answer: By Kiddush Levana delaying to right after shabbos gives praise to the mitzvah of Kiddush Levana itself. But by tefillin, wearing it with the tallis doesn’t bring praise to the mitzvah itself of tefillin.