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

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