If this is your first router, then I'm going to disagree with almost everyone, and say you should get a cheap router bit set.
Reasons? If you've never used a router before, you will make some mistakes. You may even destroy a bit or two. Better to wreck a $5 bit than a $50 bit.
You can use the cheap bits to learn how the router works, and how you work with it.
Also, you can use the cheap set to see what bits you'll actually use, and then replace them with quality bits. Sure, you could try & work out what bits you're likely to need, but you won't get that 100% right for you. Even if you only buy one quality bit that you don't use, you're going to be more out of pocket than the cost of a full cheap set.
I bought my first router (admittedly not a Festool one!) around 12 years ago. I also got a cheap 20 piece bit set. I destroyed a couple of bits almost straight away by trying to remove way too much material in one pass, and quickly learnt what the limitations of that router were. I've bought quality bits ever since to replace some of those, and others that I needed for specific applications as I went along. As for the rest, I still have probably 50% of that set, that I use very rarely, or have only ever used once. Indeed, there were 2 dovetail bits that have never been used. But I've never bought a high-priced bit that I haven't used.
For those reasons, I'd recommend a basic, cheap set.
