While a little more running time is a good idea (as is a lower pitch prop), I'd ask if your low speed needle is set just right. This is fairly easy to determine:

Let the engine sit at idle for 10 or 15 seconds
Advance the throttle to full QUICKLY
If the engine comes up smoothly to full throttle you're fine
If the engine quits very quickly on the way up, the low speed needle is too lean
If the engine coughs , spits and hesitates on the way up, the low speed needle is too rich

If you need to adjust the low speed needle to get that smooth transition, don't forget to readjust the high speed needle when you're finished.

Also, make sure your glow plug is good. Sometimes a weak plug can give you the same symptoms.

One other quick test that might help. When you start your engine let it run a few clicks above idle for 5 seconds then remove the glow starter. If the engine slows noticably you either have the low speed needle too rich or a weak plug.

This all sound more complicated than it really is. You'll get it ...... have faith! Best of luck