In Ikariam, the priority of units in battle is determined by the deployment order. Units deployed first go to the front lines and have priority over units deployed later. This means that if you wave SGs after already deploying hops, the SGs will likely not make it to the front lines and may end up getting killed before they are able to participate in the battle.
It is therefore recommended to wave SGs before deploying any other units to ensure they have a chance to make it to the front lines. Additionally, it is important to consider the enemy's defending units and fortifications when planning an attack, as SGs may not be the most effective unit to use in all situations.