How long does it generally take for the IRS to review audit documentation and release a refund?

I was selected for audit for my 2016 tax return prior to my refund being approved/released. I had the option to mail or fax my documentation. I faxed 86 pages including all my records for my income (I babysit), a letter from my church verifying my children resided with me alone, and a letter from my children's father verifying I am the primary custodian and supporter of them. Generally speaking, how long after documentation is submitted should I hear something? This is the 1st year I have been audited and nothing has changed except my filing status. I filed single instead of head of household this year because I did not keep all the records needed to file HOH (in case of review).