Hanafi
The sources give no view for it here.
وقت ثبوت الشفعة
هل تثبت الشفعة قبل تمام البيع بالتفرق أو التخيير؟
Each school’s answer
In our wordsHanafi
Not stated in the sources
Maliki
Not stated in the sources
Shafi'i
Not stated in the sources
Hanbali
Not stated in the sources
The texts
١٦١١ - مَسْأَلَةٌ: وَلَا شُفْعَةَ إلَّا بِتَمَامِ الْبَيْعِ بِالتَّفْرِيقِ أَوْ التَّخْيِيرِ لِأَنَّهَا لَيْسَ بَيْعًا قَبْلَ ذَلِكَ وَهُوَ قَوْلُ كُلِّ مَنْ يَقُولُ بِتَفَرُّقِ الْأَبَدَانِ. [مَسْأَلَة مَا يَقْطَع الشُّفْعَة]
From the schools’ own books
Maliki
The sources give no view for it here.
Shafi'i
The sources give no view for it here.
Hanbali
The sources give no view for it here.
What is «in our words» is our standard wording; the books’ texts stay as they are.