We analyze the impact of deadline policies on student submission timeliness and success in a self-paced online programming course. The course is for learning a second language (C) after Java or Python and assumes some knowledge of data structures. It targets undergraduates in a four-year computer science degree program. We measure changes in student submission timeliness, assess pass rates, and analyze the effects of a hard mid-term deadline across various submission policies. One analysis measures the percent of time through the term when students submit their assignments. This measure highlights student procrastination. Another strategy examines the fraction of students who turn in assignments on time or within specific time frames (within one week, etc.) of a stated or suggested deadline. This offers insights into the impact of deadline policies on submission timeliness. For course offerings without deadlines, we used notional deadlines corresponding to what we would suggest, for comparison. The deadline policies in this study were: no deadlines, suggested deadlines, deadlines with minor penalties (sometimes allowing one low score to be dropped), and deadlines with minor penalties plus a hard mid-term deadline. We assess the impact of each deadline policy on student procrastination and course completion rates, including effects on withdrawals and incompletes. Defining the pass rate and accounting for student attrition is crucial to accurate assessment of deadline policies. Our findings contribute to understanding of effective instructional design in self-paced online learning environments. A key result is that judiciously chosen deadline policies can improve student timeliness and pass rates.