There are a few ways to play it. I've considered trying to look for a favorable rate the other direction. It wouldn't be 1:1, but rates will certainly move closer to that. By going back & forth, you could grow "for free," but make sure to account for the fees.

As for when you can exchange 1:1, the timing is very up in the air. The most pessimistic nay-sayers will tell you it could be years--if ever! However, many people are starting to say the merge could happen this year, which would mean within the next 6 months.

There was recently an article about the difficulty time bomb, which has been delayed to later this year. An article on Decrypt quoted one of the Ethereum developers as saying that delaying it again wouldn't be necessary if all goes according to plan. This supports my personal belief that it's coming sooner than later, i.e., this year. Obviously, there are no guarantees, though.