Nafil Prayers Before Asr
Please note that there is no such thing as an obligatory nafil prayer. All nafil prayers are discretionary. If you offer these prayers, you shall get rewarded. However, if you do not then you won’t be questioned about them. Next, there is no problem in offering nafil prayers after asr. The only forbidden times for prayer are around the time of sunrise and sunset. For details please see: Discussion 1626