Rookie Question regarding DDNS & Adblock

Hello Community,
I have a (small) problem, my WRT 3200 ACM with 22.03.2. In use is under other packages, Adguard and DDNS, and I love it, but there is one small problem, I need somehow, to startdelay DDNS as AdGuard needs 2-3 Minutes every time on reboot, to gather blocklists, processing, merging etc.. and this causes somehow DDNS to not start correctly..

I have to restart it in Terminal by command (/etc/init.d/ddns restart) or going via Luci DDNS Menu and press reload, then all is fine, and it updates WAN IP all correctly.

What is the best way to solve this, for it starts with a for example 4 minutes delay?

I have indeed investigated a little bit, and some say, add line to rc.local ->
sleep 240, /etc/init.d/ddns restart

Its a rather small problem, I know, all is fine so far, but solving this, would make everything work perfect

but also found some people, saying, that doing that in rc.local isnt good!?

Has somebody, a clue, how to solve this and would give me please a hint please?

Thank you in advance, and Thank you for your patience with this Rookie Question!