The first level enchantment spell Command specifies that the action the target is forced to take happens
on its next turn
The second level enchantment spell Suggestion, on the other hand, says that for the target,
On a failed save, it pursues the course of action you described to the best of its ability.
Since the action is not specified as starting on its next turn, it is possible that it could be started or even completed before its next turn, provided the action was one which it could take even while not on its turn. Furthermore,
the spell ends when the subject finishes what it was asked to do.
How should the GM, or possibly the GM playing as the target of the spell, interpret "to the best of its ability"? Is it better to act sooner, before its turn, or wait until its turn so as to have more options or more powerful options available in order to complete the suggested course of action?
As a specific example, suppose a target with Extra Attack was subject to the suggestion "attack the guard". The guard then leaves the reach of the target before the target’s turn. The target could choose to use its reaction to make a single attack, which would end the suggestion effect. The target could also choose to wait until its turn, allowing it to take the Attack Action, attack multiple times with Extra Attack, and possibly use other abilities such as bonus actions or movement to make its attacks more effective.
Of these two choices (less sooner or more later), which would be considered pursuing the course of the action to "the best of its ability"?
This question is related, and asks (in part) whether the target will perform actions before its first turn. However, my question is different in that asks about the resolution of the "to the best of its ability" clause by supposing a tradeoff between acting sooner for less effect or later for more effect.