Do you mean long term or short term? The general suggestion for small investors* is to wait until prices have settled down for longer term investments. From similar past flotations there has been a massive spike in the first day or two, may be worth buying a few for a few hours before selling again if you have an account that allows thats oct of thing.
£24 a share makes no difference than 2p a share if it goes up 10%... You just get less of them for your investment.
* Not sure if it was mentioned in that article, didn't read it...