Based on our son's experience, you'll want to add the length of your "A" school (3 or 6 months I believe) to the nominal length of Power School (6 months). Then throw that number out the window and don't even think about making wedding plans until you actually start Power School (and remember you've got at least another 6 months at prototype plus ELT or Welder schools should you be selected).
As a data point: Son of DadofFutureNuke (now an actual ELT) encountered multiple delays, some common, some not:
- Hold to class up for MM A-School - about 2 weeks as I recall and typical
- Hold to class up for Power School - I'm thinking more than a month, but I could be way off
- Hold for Prototype - 6 months (yes really)
The last one is completely unpredictable - he didn't know when he would go for sure until he ended up in the last group. When you add it all up including basic, he spent roughly two years "in the pipeline".
Another data point: Son found the woman he's likely to marry late in Power School. He completed the pipeline, got assigned to a boat being overhauled, rode another to get qualified and is now back at the shipyard doing whatever it is ELTs do when the plant is shutdown and *finally* renting a house and doing the "live together" thing to make sure they can stand each other on a daily basis. He's been in almost 3 years at this point.
Good luck and thank you for your service!