Primavera P6 Answers

Create zero duration activities with calendars that have only one work hour in a week on Monday night.

Add these activities as preceding to your activities that must start on Mondays.

All inbound dependencies to your activities starts must become preceding to created zero duration activities.

This advice will not work if your activities have predecessors to their finish points.

 Figure 1

 Figure 2

For a better view hover the figures and click.

Figure 1 shows how with calendar lags can be done. This does not require additional milestone.

Figure 2 shows how with activity lags can be done. This requires an additional intermediate milestone.

The special calendar was created with a very short duration very early on Monday, 0 duration on the remaining days of the week.