Hanafi
The sources give no view for it here.
الوتر قبل صلاة العشاء
هل تصح صلاة الوتر إذا أُديت قبل صلاة العشاء؟
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
٣٠٦ - مَسْأَلَةٌ: وَمَنْ صَلَّى الْوِتْرَ قَبْلَ صَلَاةِ الْعَتَمَةِ فَهِيَ بَاطِلَةٌ أَوْ مُلْغَاةٌ؛ لِأَنَّهُ أَتَى بِالْوِتْرِ قَبْلَ وَقْتِهِ، وَالشَّرَائِعُ لَا تُجْزِئُ إلَّا فِي وَقْتِهَا، لَا قَبْلَ وَقْتِهَا، وَلَا بَعْدَهُ، وَبِاَللَّهِ تَعَالَى التَّوْفِيقُ؟ . [مَسْأَلَةٌ وَقْتُ رَكْعَتَيْ الْفَجْرِ]
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.