on my experience kahit ilan boss as long as available pa sya at wala ka ng current unli data promo..
example, for the month of July.. hanggang July 18 lang to pwede claim.. so anytime pwede ka mag avail on or before that date.. pero in my case naka reg pa ako sa unli299 nung last month (June) at mag expire ito sa katapusan ng July, since may current Unli pa ako, maghihintay pa akong maexpire ito bago maka reg ulit.. pero by the time mag expire current promo ko, tapos na rin ang promotional period..