(Still got time)
Umm ul Mu’mineen Aysha (RA) states: Rasulullah (SAW) used to remain in Itikalf in the last 10 days of Ramadhaan.
Note: Men in the Musjid, woman at home. If one cannot do so for the last 10 days, at least try and spend a single day in the form of nafl Itikalf. May Allah Accept all our good deeds.