When do you put straw around strawberries? Somebody sent me six strawberry plants years ago and now I have an actual patch by default. Too many times I've gone to pick a berry to find a slug has beaten me to the berry.
I use cedar mulch pretty much exclusively because it is cheap and readily available here. The organic gardening fanatics tell me it is what is preventing most bugs from getting to my strawberries so you might want to try that. I have never had slugs.
A caveat that I should mention is the birds often get to mine before I do anyhow and it doesn't do anything for ants.
I like to wait until the weather warms up a little. Mulch during cold weather gives insects shelter so they will already be in your strawberry patch when they are ready to become active. Also, I put out lids with beer in them in various locations in my strawberries. The slugs (little drunkards) love the stuff. The will crawl in and then are unable to get back out so they drown. This is relatively cheap and an organic approach to your slug problem.