You should definitely learn pinyin and the tones (four and the neutral tone) at the beginning, but I would suggest learning these while learning vocabulary and grammar. It won't be long before you come across all the tones, so that is something you should get used to very early on, but as for the pinyin, I would learn as you go and then cover the rest of the pinyin a bit later on. If you want any help starting to learn Chinese, I have a free online video course and Skype group, so contact me if you are interested.

Of course Pinyin and four tones is the first step of your Chinese learning and they are important as well.The four tones will follow your Chinese study all the time.Pinyin will make Chinese study easily and quickly.I'm a Chinese teacher,my students need to use Pinyin for 2years when beginning to study Chinese.Hanzi is very difficult for the beginners.You can not read Chinese without Pinyin at first.

If you learn pinyin well ,everything is not a problem.