Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: When a person goes into bowing and walks to join the row: if he enters the row before the people raise their heads, he is to count that rak'ah; and if the people raise their heads before he reaches the row, that person is not to count that rak'ah.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Zayd bin Ahmar, and I have not found anyone who mentions him.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2405