There is not specific time for IDNs to function in emails. The technical standard is under development in the IETF (Internet Engineering Task Force, www.ietf.org
) and has reached what they refer to as "experimental status". What this means is that they are looking for email application developers that are interested in implementing the standard and experimenting with it. Some implementations have been made already, one for example is available at: http://global-email.info/intro.html
The next steps in finalizing the technical standard is that the experience gained in the initial implementations and usage will be reported back to the IETF working group on this topic, they will review and potentially modify the technical standard, after which it will be released as a standard. Once a standard it is likely that other email clients/software will implement the standard and in that way enable the use of internationalized email.
ICANN has nothing to do with the development of the technical standard, expect for supporting the work in the IETF. ICANN further has no control over the implementation of technical standards done in application software, such as the email clients. Hence it is difficult to give any additional time estimates.
I hope this answers your question, but please let me know if you have any additional questions.
Senior Director, IDN