This article dwells upon the issues of providing project timely completion as well as key project milestones. In many cases project deadline exceed leads to catastrophic outcomes for the aims and results of the project. Thus, the present article deals with the relevant issues of project schedule control, methodology study based on application of Schedule Timeliness Index and Schedule Progress Index, indicating upon reaching the critical value of extreme deviations from the forecast project duration of targeted project implementation at any moment of time. The suggestion herein is to calculate the minimum possible durations for each project activity and estimate the project duration safety margin coefficient. Based on the safety margin coefficient value it is suggested to define the border values for project shift from one status to another upon criteria of its timely completion possibility. The suggested methodology can be recommended for use by construction project managers in order to prevent a potential failure of project completion deadlines. The system indicating critical project time variance enables to initiate the process of project schedule adjustment before point of no return and herewith prevent project failure. The studied methodology was implemented in modern project management software sphere.