Welcome to FDMB!
You have come to the right place!
I'm still a "newbie" and am not using Lantus on my sugar kitty so I won't give you dose advise except what someone already said..."start low and go slow".
It works and keeps your kitty safe. Since I've joined the forum in September of 2014, I have read stories of people asking for help cause their kitty has gone too low. Scary and something I pray doesn't happen to Hank. So I'm probably over cautious but hey, that's ok.
I would recommend testing before each shot (AM and PM) and then again for sure at +5 and +7. If you want to do a +2 or +3 or any others in between, Great! The more data the better!
I tested Hank a lot when He first started insulin but I wanted to make sure he stayed safe. Glad I did cause there was a couple of low numbers that I didn't expect.
It's also good practice at testing.
Once you get the hang of testing, join a support group. There are two for Lantus to choose from: tight regulation and relaxed. That will help sooooo much with dosing questions and any other questions that you may have. You can go ahead and look and read some of the posts on the groups.
Hank and I are in the ProZinc support group. It really has helped me.
I'm sure others with dosing for Lantus will be along shortly to help you.
Hang in there! It takes patience. You're doing fine, you found this forum!
Kimmie