With XATA the Base-Build-Peak (BBP) option defaults to 120 days out from today.
If the target event were on June 15th the traditional base period (all endurance) in BBP couldn’t begin until February 16th.
In the meantime, you could select XATA Continuous, set improvement rate to Off-Season, and ride however you like. That might include less cycling and more gym work in preparation for your progression starting in February.
You could set Focus Duration to 20-minute power (Sprint TT) for the least intensity recommended on HIT days,
In XATA Continuous mode you’re in charge. You’ll get adaptive training advice based on calculated form (v.tired to v.fresh) but you can choose your own path and over-ride the advice when you want. You can be selective about which workouts you choose and their level of difficulty.
If you instead generate an XFAI forecast with June 15th as the target date the periodization logic will kick in and show a dip to start with.
Here’s an example test forecast I ran for a June 15th Hilly Road Race 3+ hours.
Notice how the Focus Duration starts out low (dip to easy; more LIT) then zeroes in on Mixed Puncheur (4 minute power) HIT in June.
Also notice the frequency and TL increasing along with distribution of high/peak XSS (yellow/red on HIT day matchsticks).
An XFAI plan isn’t traditional all-endurance Base phase, but you do start out with a lighter load.
You can run your own test scenarios. You don’t need to save them. Zoom in out on chart and hover over each matchstick to see details. Also isolate the chart entries by tapping on the key below the chart. Example (60 day Goal):
XATA follows a more traditional phased progression, but the same principles apply and run in background with a blank calendar. Click here to see how Focus changes during a BBP progression.
I posted a chart of XFAI/XATA differences here – Forecast AI vs Continuous Adaptive — better load & recovery management? - Training - Xert Community Forum
With this many months out from your event date you could experiment and try all of the above. 
I.e. flip between XATA and XFAI with different settings and note what each does over a week or two. Just keep in mind you want your XFAI plan or XATA BBP progression to include enough wiggle room to support a reasonable rise in TL over the term. No need to reach max weekly hours until Peak phase.
Enjoy the ride.