it all depends on the health of the plant and the strain really. if no issues and a resilient strain, you could defol more. since youre starting out id do no more than 1/3rd of the plant at a time and see how she responds over 3-4days.
start off with the largest fan leaves covering up other bud sites/laying on top of other fan leaves. i also try to defol fan leaves that are growing inward/towards the middle of the plant. only defol what you absolutely must and try to lst and tuck the rest of the leaves to expose as many bud sites to light.
some plants ive done i had to defol almost every other day, others on a week or more basis. but the most important thing is to remove as little as possible to start and watch how she responds. also dont defol if you have a deficiency or other issue going on as that may over stress the plant.
youre already a couple of weeks into flowering so i recommend doing a little at a time. next round, try to defol earlier in veg and be mostly done with defoling by week 2/3 of flower.