I use a sanitized turkey baster and hydrometer combo before pitching yeast in the low 60s (F) then once again before bottling, usually 3-4 weeks later. Sometimes I'll take a sample mid-way. But I find that after hundreds of brews, my FG is usually on point at 3-4 weeks anyway. The side benefit is further conditioning and cleaning up of any off flavors that were initially expelled by the yeast.
I usually re-incorporate the 1st sample back into the main volume (pre-ferm), then drink the 2nd and 3rd samples to see how the flavor is developing. Never had an infection due to improper sanitiation.