Your finish time will depend on dozens of different factors, so it is very hard to predict. A training plan is just one part of the equation. The biggest determinant is your starting fitness and ability.
Improvements in bike and run fitness happen gradually over a long period of time, if you train and recover effectively. There are no shortcuts unfortunately, even if you trained to the absolute best of your ability it might take you four or five years to reach your full potential.
First and foremost you need to pace it right based on your race day fitness, rather than what you hope to achieve. If you chase a time, you will probably race too hard and then suffer later.
The best thing to do is look for gradual small improvements in your key swim, bike and run metrics. Such as Functional Threshold Power and Threshold Run Pace. If you're aware of these, you'll have realistic expectations going into your races.
If you still want some idea of your bike time, you could use www.bestbikesplit.com. For your first one it's better not to set too many expectations. Just use the race to build experience.
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