That's great news!
How long do you need to continue doing this?
I'm sure it varies quite a bit between LO's. Why don't you post your routine in EAS format and we can see if any tweaking needs done. When my DS was this age, it seemed like we were increasing A time constantly! Having the right A time can really help with nap length. If we're dealing with UT, no amount of shh/pat, HTTJ, etc will put him back to sleep (at least, not for my little guy!). In the meantime, keep up with HTTJ...I'll keep my fingers crossed that you continue to see success with it xoxo