إِذَا لَبِسْتُمْ and إِذَا تَوَضَّأْتُمْ introduce two distinct situations, while a single command, فَابْدَؤُوا, applies to both. Arabic can join related conditions without needless repetition.
Example 1: Begin inserting the right arm when putting on a garment.
Example 2: During ablution, wash the right side first where paired limbs are involved.
Hadith 263 will explain a different sequence for removing footwear; the two actions should not be confused.