If you're in Life Science, don't worry. Setting up lab and getting reagents all take time. And even if you have all those things now, you also can't start straight away cos you really need to know what you're doing and how you're doing it.

Your supervisor is right - take the time now to research your project and what items you need. Then how to conduct the experiments. Don't just jump into it and copy from the manual - know what you're doing. Most likely you'll fail and that's why you must know what you're doing so you can troubleshoot.

You also research to find out what you need. E.g. suddenly at the last step say you need this chemical X and you don't have it, then you need to order and wait for few weeks. Or that you find that the protocol is actually for genomic DNA and your sample is mitochondrial DNA.

tl;dr - Don't worry. In fact got some places spent up to 6 months just reading literature and follow senior to learn and see how they do.