You should have 60 days, but your ISO should confirm this.
Please see below from the USCIS Q&A RE: Extension of Post-Completion Optional Practical Training (OPT) and F-1 Status for Eligible Students under the H-1B Cap-Gap Regulations
"Q5. Is a student who becomes eligible for an automatic cap-gap extension of status and employment authorization, but whose H-1B petition is subsequently rejected, denied or revoked, still allowed the 60-day grace period?
A5. If USCIS denies, rejects, or revokes an H-1B petition filed on behalf of an F-1 student covered by the automatic cap-gap extension of status, the student will have the standard 60-day grace period (from the date of the notification of the denial, rejection, or revocation of the petition) before he or she is required to depart the United States.
For denied cases, it should be noted that the 60-day grace period does not apply to an F-1 student whose accompanying change of status request is denied due to the discovery of a status violation. The student in this situation is not eligible for the automatic cap-gap extension of status or the 60-day grace period. Similarly, the 60-day grace period and automatic cap-gap extension of status would not apply to the case of a student whose petition was revoked based on a finding of fraud or misrepresentation discovered following approval. In both of these instances, the student would be required to leave the United States immediately."
This information is provided as a courtesy based upon the limited information provided in your post and does not constitute an attorney-client relationship.
Generally you have 60 days. It is best to confirm with your DSO.
Alexus P. Sham email@example.com (917) 498-9009. The above information is only general in nature and does not constitute legal advice. It does not create an attorney-client relationship.
60 days from the date of the withdrawal.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.