Could be anywhere between now - 9 months plus lol. I saw that the current log/timeline for SSBI is about 7 to 9 months anyway, would just wait diligently since you've signed and is a done deal pretty much.
I'm doing my OPI in probably couple of weeks and on the home stretch, practicing my native tongue like a fool right now.
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Bio Date - 02/22/18 (walked in 2/15)
Expiration - September '18
Approved - 04/09/18
Naturalized via MAVNI | April 2018