My DSisIL got engaged last Christmas Eve, (it was a complete surprise - so much so that she was still shaking sitting in her Mum's kitchen 3 hours later!! A good surprise, but still a shock!). Their wedding is next June, so almost exactly 18 months. They booked the hotel first, relatively quickly but it still took a couple of months to check out all the local ones and make decisions. She just gets on with bits and pieces for a few weeks and then lets life take over again too. All pretty much organized at this stage except BM and FG dresses (we don't care what DD wears, if SIL can persuade her not to wear a tracksuit, we're happy, but other SIL is very fussy about what her 2 DDs wear and all have to match - BMs it's more a case of SIL and her 2 BMs agreeing, as the FG will be cream dresses with a ribbon sash to match BM colours - so the 2 searches are separate). And of course, MIL still has to get her outfit (and so do I come to think of it! Post Christmas sales were great for the last wedding we had).
One of my DSis's got engaged in July, also a surprise. She is organizing for Sept next year in Rome and has already bought her dress and working away on bits. BM and MoHonor have to agree dresses yet (I have to meet BM - not a clue what I want let alone how to work with her as we are completely different styles), but she has got her own dress. I think DSis has been persuaded (by the various parents involved) to go pretty much no DCs (except stbBIL's DNephew as ringbearer), but she's torn on that and doesn't want to exclude them (we are all more thinking of the reality of bringing them to Rome in school time for 3-4 days, and entertaining them in a hotel and not the most child-friendly city, not trying to exclude them but being realistic). Rome was only decided 10 days ago, so it's basically going to be all done within 10 months.
Lots of stuff is lovely but optional. The things that are important are Bride, Groom, celebrant and 2 witnesses. After that, having your friends and family is nice, and maybe a bit of music (but local music school may have groups, church may have a choir/organist/soloist etc or your iPod can have a playlist on it). A bit of grub doesn't go astray. The wedding party (B, G, BM, BM, etc) can be fussy and formal or relaxed and quite casual - depending on what YOU like. A handful of flowers, or huge bouquet - you could organize those the week before. Sitting down to think of some nice things to say does take time admittedly, especially if you are not used to it. All the rest are extras - which are lovely, but you don't have to have them.
So first of all, you and your Fiancé need to sit down and decide what you both want. Not what others want - you 2. What type of ceremony, and what kind of party afterwards, and how formal you want to be (both in outfits and the day itself). Then work backwords from what takes longest to do, and just do lists of what you would like and ideas of how to achieve it. And start slowly looking and ticking off those items one by one - you eat the elephant best by taking one bite at a time!!