I just had a frenectomy and fiberotomy. when will the space close?

After braces: Spaces do not usually close by itself. Time depends on your teeth, jaw, bite and other factors.

As force is applied: I must assume that you are also having concurrent orthodontic treatment with braces or clear aligners. The space will not likely spontaneously close - some type of orthodontic force will be required. Depending upon the size of your diastema or space, it can typically be closed within weeks.