I think that it is better to buy immediately after IEO. In addition, it is not always possible to buy during IEO. But most of all profit will bring participation in the beginning. So if you have the opportunity to join in time, then you can do it.
I doubt it. IEO tokens when trading starts can be probably pumping. So if you buy during its time of trading, hence youre buying it at a very high price unless, you will know the potential movement of it, of course by TA method.
I suggest to OP that wait for it to go down first close to it IEO price then, sell when the price go up again. Buying after IEO done is actually a risky time as you know IEO tokens are having a good ROI on their first week. Observe first, if you think it will go up then go risk. Youre confidence should be leveled with it. Overconfidence will only be resulted to loss, better be safe than sorry.
I choose investing with IEO than ICO because faster trading for IEO coin than ICO, IEO just open selling few week and after IEO ended directly listing with exchange market where they listed for IEO, for ICO we need phase selling from pre sale until main sale with success, if not success with hard cap maybe phase for selling continue for several weeks later.