Ok this template should work for your next day at all times.
{%- macro getalarm(offsetday=0) %}
{%- set day = (now().weekday() + offsetday) % 7 %}
{%- set offset = offsetday * 86400 %}
{%- set fmat = 'd' if day in range(5) else 'e' %}
{%- set hour = 'input_number.alarmclock_w{}_hour'.format(fmat) %}
{%- set minute = 'input_number.alarmclock_w{}_minute'.format(fmat) %}
{%- set alarm = states(hour) | float | multiply(3600) + states(minute) | float | multiply(60) %}
{%- set time = now().hour * 3600 + now().minute * 60 %}
{{ (offset - time) + alarm if offsetday else alarm - time }}
{%- endmacro %}
{%- set weekday = is_state('input_boolean.alarmclock_wd_enabled','on') %}
{%- set weekend = is_state('input_boolean.alarmclock_we_enabled','on') %}
{%- set weekdays = [0,1,2,3,4] %}
{%- set weekends = [5,6] %}
{%- set day = now().weekday() %}
{%- set nextday = day + 1 if day != 6 else 0 %}
{%- if nextday in weekdays %}
{%- if weekday %}
{%- set offsetday = nextday %}
{%- elif weekend %}
{%- set offsetday = weekends[0] %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{%- elif nextday in weekends %}
{%- if weekend %}
{%- set offsetday = nextday %}
{%- elif weekday %}
{%- set offsetday = weekdays[0] %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{% if offsetday != None %}
{% set offset = offsetday-day if offsetday > day else offsetday - day + 7 %}
{% set today_alarm = getalarm() | float %}
{% set next_alarm = getalarm(offset) | float %}
{% if today_alarm > 0 %}
{{ today_alarm | timestamp_custom('%H:%M', False) }}
{% elif offset == 1 %}
{{ next_alarm | timestamp_custom('%H:%M', False) }}
{% else %}
{{ (next_alarm // 86400) | int }}:{{ next_alarm | timestamp_custom('%H:%M', False) }}
{% endif %}
{% else %}
Not set
{% endif %}
This template should calculate the days until your next alarm.
{%- macro getalarm(offsetday=0) %}
{%- set day = (now().weekday() + offsetday) % 7 %}
{%- set offset = offsetday * 86400 %}
{%- set fmat = 'd' if day in range(5) else 'e' %}
{%- set hour = 'input_number.alarmclock_w{}_hour'.format(fmat) %}
{%- set minute = 'input_number.alarmclock_w{}_minute'.format(fmat) %}
{%- set alarm = states(hour) | float | multiply(3600) + states(minute) | float | multiply(60) %}
{%- set time = now().hour * 3600 + now().minute * 60 %}
{{ (offset - time) + alarm if offsetday else alarm - time }}
{%- endmacro %}
{%- set weekday = is_state('input_boolean.alarmclock_wd_enabled','on') %}
{%- set weekend = is_state('input_boolean.alarmclock_we_enabled','on') %}
{%- set weekdays = [0,1,2,3,4] %}
{%- set weekends = [5,6] %}
{%- set day = now().weekday() %}
{%- set nextday = day + 1 if day != 6 else 0 %}
{%- if nextday in weekdays %}
{%- if weekday %}
{%- set offsetday = nextday %}
{%- elif weekend %}
{%- set offsetday = weekends[0] %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{%- elif nextday in weekends %}
{%- if weekend %}
{%- set offsetday = nextday %}
{%- elif weekday %}
{%- set offsetday = weekdays[0] %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{%- else %}
{%- set offsetday = None %}
{%- endif %}
{% if offsetday != None %}
{% set offset = offsetday-day if offsetday > day else offsetday - day + 7 %}
{% set today_alarm = getalarm() | float %}
{% set next_alarm = getalarm(offset) | float %}
{% if today_alarm > 0 %}
0
{% else %}
{{ offset }}
{% endif %}
{% else %}
Not set
{% endif %}