I recently took my dog (jasper) to the vet bc he’s been experiencing a lot of separation anxiety (barking and howling for hours on end, excessive panting and drooling). He was put on Gabapentin and trazodone. We were instructed to give him both about 1 hour before we leave. Yesterday was the first day and it was great! He was chilling people watching all day from his spot of the couch with no barking. The chillness lasted from about 9:30am (30 mins after i gave him the dose) till about 4pm or so, around the time my partner usually gets home. I go to the gym about 3 days a week, in the morning for about an hour (7:45am-8:45am) and during that time jasper is barking non stop till i get back. My question is, when would be, or if there is, a better time to give him his meds so he’d experience less anxiety when i go out to the gym. For reference no one is home/ everyone is at work from 10am-4pm.

Jasper is an 8 year old german shepard collie (smooth) mix

PS i’m not looking for any “distraction” and training recommendations. My dog is used to being alone in a house when everyone goes to work, but isn’t used to our new apartment yet.