That sounds like a good treatment to me, except I'm not a big fan of the spikes. They dissipate very slowly, and in a limited area.
It's actually better to maybe break up a couple of spikes with a hammer or something and sprinkle it over the root area of the shrub. This will allow the fert to dissipate faster during this time of rapid growth, and also to get to more of the root system.
Don't forget the roots of your shrub extend out beyond the reach of the branches, not just in by the base.
A pelleted, time-release fert is a better choice going forward. Something like Nutricote or Osmocote. Amending the soil regularly with compost will help with soil pH balance, too.
