Time estimation is always considered as one of the success factor for any software project. The study is related to software projects failure and the role of time estimation in the success of any software project. The objective of this research is to find all those factors that can effect timely delivery of software and increase the actual time estimation. Findings these factors are necessary so that actions can be taken in the beginning of the project. Systematic Literature Review (SLR) will be conducted to achieve the aforementioned goals. SLR being more formally planned is different from ordinary literature review. SLR protocol is developed and executed in different digital libraries and as a result of inclusion and exclusion criteria applied, we have finalized more than 20 papers. The final output will be the extraction of all those factors from different research studies that can influence the estimated time of projects. The results will help us to identify any research gap where more work is possible for successful and timely delivery of software projects.