Our Prophet (peace be upon him) has never singled out 15th Sya'aban as the day that one should fast. Instead he fasted as much as possible throughout the whole month of Sya'aban as mentioned by Aisyah r.a.:
“I never saw the Prophet (peace be upon him) fast an entire month except for the month of Ramadhan. I never saw him fast more often in any other month than he did in Sya'aban.” [Sahih al-Bukhari (1969) and Sahih Muslim (1156)]. <-- I found this from a blogger, Dari Mata Seorang Muslimah.
Later, we're gathering at Yanti's place, having the plans to have our break fast (sungkai ~ some of us are fasting today, including myself ~ a qadha' for our missed Ramadhan days), then a Maghrib (Dusk) Juma'ah Prayer, recital of Surah Yaasin for 3 times and proceed to Isya' (Evening) Juma'ah Prayer.
May we have the blessing from Allah The Almighty, also blessing the bride and groom on their wedding tomorrow. Ameeenn ...
Ahlan Wa Sahlan Ya Ramadhan :)
PS: It is a Makhruh to fast on Friday without any purpose. Some olds have misunderstood this by saying that, "If you want to fast on Friday, you should start fasting on Thursday and continue fasting till Saturday". It is a Sunnah to fast on Monday and Thursday but to qadha' our missed Ramadhan days, it can be done on any of the days, including Friday. Therefore, to fast on Friday "you must fast on Thursday and Saturday" does not exist. It is merely confusion. <-- I confirmed this from an Ustazah, who is also my colleague, this morning. Wallahu'alambissawwab :)