The signs of Judgement are aimed to drag the attention of people that the day when they are going to be questioned about what they did in life is approaching so they repent before major signs are witnessed cause that’s when repentance won’t be accepted as in the following verse from Surah Al-An’aam/The Holy Quran.

هَلْ يَنْظُرُونَ إِلَّا أَنْ تَأْتِيَهُمُ الْمَلَائِكَةُ أَوْ يَأْتِيَ رَبُّكَ أَوْ يَأْتِيَ بَعْضُ آيَاتِ رَبِّكَ ۗ يَوْمَ يَأْتِي بَعْضُ آيَاتِ رَبِّكَ لَا يَنْفَعُ نَفْسًا إِيمَانُهَا لَمْ تَكُنْ آمَنَتْ مِنْ قَبْلُ أَوْ كَسَبَتْ فِي إِيمَانِهَا خَيْرًا ۗ قُلِ انْتَظِرُوا إِنَّا مُنْتَظِرُونَ

‏Do they then wait for anything other than that the angels should come to them, or that your Lord should come, or that some of the Signs of your Lord should come (i.e. portents of the Hour e.g., arising of the sun from the west)! The day that some of the Signs of your Lord do come, no good will it do to a person to believe then, if he believed not before, nor earned good (by performing deeds of righteousness) through his Faith. Say: "Wait ! we are waiting."