The Islamic, Muslim, or Hijri calendar (Arabic: التقويم الهجري at-taqwīm al-hijrī) is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the annual period of fasting and the proper time for the pilgrimage to Mecca. The civil calendar of almost all countries where the religion is predominantly Muslim is the Gregorian calendar.
All our timing calculations in Islam are based on lunar calender, so the time of breastfeeding is two lunar years.
You can breastfeed your child for slightly more than two lunar years and you can also do so according to the western calender.
Although the two years of breastfeeding has been recommended in the holy Quran, it does not necessarily mean you cannot wean your child before that. When you are introducing solid and nutritive foods, you can gradually minimise the breastfeeding until your infant is completely weaned.