There are such things as a knitting class, find a yarn store (an ACTUAL yarn store, not just an everyday store that sells yarn and other things) and usually the ladies (sometimes men, mostly ladies) will either help you get signed up for a class or may even just give you a pointer or two to begin knitting.
My advice: When it comes to holding the yarn, do it how YOU feel comfortable, especially when you're first starting out. Forget about tension problems, forget about the ball, just focus on the needles and how you find it best to wrap the yarn around them appropriately. When I began I had some mutated form of continental yarn holding and 5 year old who couldn't quuuuuuite grasp the idea of holding the yarn properly. (Note: I was 16 when I first learned to knit)
For me getting the knack of knitting was like riding a bike - I couldn't QUITE understand how to do it, then one day I was watching my grandma speed through a sweater for my grandpa and it just *clicked*, nothing special, she didn't say anything, I just understood how it should work and a way I went.
4 months should be plenty of time to get it done, but your boyfriend will love the gift no matter when he gets it because YOU made it for him. I know this for a fact
told my ex once that I'd knit him a pair of mitts for christmas...he got them in July. He couldn't use them for like 6 months but he appreciated the gesture none the less.