There's more to it than that. Iran's intent is for only Iran to use the Strait. This action by DJT is to level the playing field so that either nobody can use it (first) or everybody can.

That's the war starting today, nothing else matters and being in no rush to get to this part was a strategic decision. Everyone expected it on day 1. Reasons for waiting are only starting to come into view; we'll see if it was a good decision.

I think there aren't any mines, simply because Iran relies on the entire waterway, too. Most mines aren't confined to a precise location. The major exception lie dormant on the bottom and (theoretically) launch themselves up into ships, under predetermined conditions. The best time for these to have been laid would have been when DJT first sent aircraft carriers, over a month before starting the war. These are the most expensive type of mine, and hopefully what Iran has the fewest of. Sweeping this type is also the hardest.

Certainly the region needed to be swept. (Or still does?)