In the first place, if one is to make the most out of massive institutional purchases of Bitcoin, they shouldn't even be buying, that is, if they think these purchases would mean rise in price. After all, by the time the news come out, the purchase had already been made. If it has an effect to the price, it must have already been factored in by the time the news came out.
I've seen Saylor's tweet a few times about Microstrategy buying bitcoin in bulk but I don't see any real impact on the bitcoin price. People may already know that it is done by the institution, and it is announced only after they make a purchase.
I have never used this kind of hype to buy because I know the power of such hype is temporary. Buying with self-analysis is the way to go even when we don't really care about the buy price if it's for the long term. In addition, the Elon hype also doesn't seem too strong at the moment so one shouldn't think of institution as a good investment moment.
Of course, hype is always temporary. You cannot hype a thing forever. So it cannot be made as a basis for long-term investment. The crypto market has abundant proofs of how short-lived hype is.
However, these institutional purchases aren't without value. These may not be short-term signals at all but these are signs that the future could be brighter. If the majority of the largest business institutions in the world would begin to purchase Bitcoin, it does not only signal for an increase in the price, it also means a much wider adoption is underway.