Age at which 85% of GFTA-2 Standardization Sample Correctly Produced the Consonant and Consonant Cluster Sounds in the Initial Position of words (p. 56)
2 /b/, /d/, /h/, /m/, /n/, /p/
3 /f/, /g/, /k/, /t/, /w/
4 /kw/
5 /ch/, /dz/ (judge), /l/, /s/, /sh/, /j/ (yellow), /bl/
6 /r/, /v/, /br/, /dr/, /fl/, /fr/, /gl/, /gr/, /kl/, /kr/, /pl/, /st/, /tr/
7 /z/, /sl/, /sp/, /sw/, /th/ (this), /th/ (thanks)
Here is a treasure trove of articulation handouts, suggestions for remediation, and more from Caroline Bowen!
Here are the specific resources for some of the most commonly misarticulated sounds:
Initial /k/ words
Initial /g/ words
Initial /l/ words
Initial /r/ words
Initial /s/ words
Medial /s/ words
Final /s/ words
Initial and final /z/ words