Unless you're a prescient genius and know when The Bottom is (hint: you're not and neither am I), it's best to invest now. Your fund may go down tomorrow, or it may go up. You're in it for the long haul. Don't try to Time The Market. You want to spend Time In The Market.
Oh this I know. I've read that many many times in this forum haha. I just figure if it goes down, it will go up, right? Is it worth waiting for that day when it could be tomorrow, next week, or next year due to the present expense ratios?
Think of it as a transfer. If you sell in one IRA and then buy back in another IRA, the only thing differentiating the transfer from a buy-and-hold strategy is the period of time between selling, transferring settled funds, and buying back in. Volatility during that brief period could make the outcome marginally bad, or marginally good; but relatively insignificant in either case from a long term perspective.
If you artificially prolong that time-gap, then you are timing the market. I would argue that
when you do this is irrelevant, and that keeping the time gap between selling and buying back in to an absolute minimum is what is important; assuming your preference is a buy-and-hold approach.