When to Write?
As per the example explained in "When to Apply" above, a student should have finished writing the GRE® and TOEFL iBT at least 3 weeks prior to the deadline (December 15, 2013 in the example).
Official Score Reporting
A student needs to report his/her GRE®Test and TOEFL® iBT scores to a university through ETS. This is known as Official Score Reporting. It takes about 2 to 3 weeks for the universities to receive the student's score through this process.
For the GRE®Test: During the exam, 4 score report recipients may be selected
For the TOEFL®: 4 score report recipients can be added through the TOEFL iBT® online registration system until 10 p.m. (local test center time) on the day prior to the test date.
However, if the student wants to report scores to more recipients, he/she may do so by filling in Additional Score Report (ASR) forms and paying an additional fee.
Hence, in our example, a student should have planned to have finished writing the GRE®Test and TOEFL® by November 20, 2013.
IELTS can be taken on any one of the 48 fixed testing days of a year
Since good scores in these tests improves the chances of admissions to good universities, a student prepares for a few months before writing these tests.
Approximately two months of professional guidance from T.I.M.E. and another two months of self-preparation from the student would imply the student should have started preparation at least four months prior to November 20, 2013 i.e. July 2013.