It looks like you are in your late 50's. What we don't know is your weight & general health.
I had the same surgery w/ 2 bypasses a year ago and quickly started doing P90X cardio but didn't push it. At the 9 month mark I went full on P90X with weights, hard cardio, etc. 5 days a week and for about an hour a day. I'm 57, 174 lbs, and you probably eat a little better than me. I plan to do "The Murph" on Memorial Day but will likely take an hour or so to do it.
I'd suggest an Apple Watch (or Samsung if an Android user). Unless your Dr says otherwise I'd push it as card as you can. If you overdo it your watch will tell you that you are going in to A-fib.
The Murph = https://themurphchallenge.com
P90X (Beachbody) = https://www.beachbodyondemand.com/?locale=en_US

Dale Gooding