The question of how neurons find each other to connect was recently studied with experimental connectomics--altering neurons and then mapping their synaptic circuits with electron microscopy--in this paper by Javier Valdes Aleman et al. 2019 https://www.biorxiv.org/content/10.1101/697763v1 , using Drosophila's somatosensory axons and central interneurons as a model.

If the OP's website Disqus worked (can't ever get the "post" button for comments after login), the above could have gone straight into the page.