What is the significance of current planning period

Business case:

1. Client has 5 years of corporate budget , till 2026. But wants to prepare forecast 2/3 times in the current financial year, 2023.
2. First forecast will be created on April 2023. Objective - Forecast should show actuals till March 23 and plan amounts for rest of 9 months till. Dec 23.
3. The second forecast will be created on Oct 2023. Objective - Forecast should show actuals till Sep 23 and plan amounts for rest of 3 months till. Dec 23.

Please advise how to achieve the above results.

Thanks in advance .