When it comes to describing something that is happening at the last possible moment, "more eleventh-hour" might be a suitable phrase. However, there are several antonyms that could be used instead, depending on the context of the situation. For instance, "planned in advance," "early preparation," "well-timed," or "timely" are all opposite phrases that could be used in specific scenarios. In essence, these antonyms refer to actions or events that are well thought-out, adequately planned, or executed timely, as opposed to those that are rushed, disorganized or hasty. Therefore, it is essential to understand the context of a situation before using any phrase that relates to a specific time or level of preparedness.