Starting a new conlang

I've been thinking about starting a new conlang project for a while now. I'm planning to do something with a bit of nonconcatenative morphology, not exactly Semitic but with some similar features, and I really want to try my hand at diachronic conlanging. Over the past few days I've put together the phonological development of the first few stages of the language.

Stage 0

Consonants

pʰ tʰ cʰ kʰ
p t c k ʔ
b d ɟ g
f s ç x h
v z ʝ ɣ
m n
     r
     l

Vowels

i      u
   a

Syllables

CV

Sound changes

V>±hightone/ _ʔ
ʔ>∅
t,d>θ,ð /VV
+asp > -asp

Stage 1

Consonants

p    t    c   k
b    d   ɟ    g
f  θ s  ç    x   h
v  ð z  ʝ     ɣ
m    n
        r 
        l

Vowels

i       u

    a

Tones

Low, High

[C]V[V]

Sound changes

i,u,a> j,w,∅/ _ V

Palatalization
pj, tj, kj > pʲ, t͡ʃ , t͡ʃ
bj, dj, gj > bʲ, d͡ʒ, d͡ʒ
fj, sj, xj, > fʲ, ʃ, ç, ç
vj, zj, ɣj > vʲ, ʒ, ʝ
mj, nj > mʲ, ɲ
rj > ʎ
lj > ʎ
cj, ɟj, çj, ʝj > cː, ɟː, çː, ʝː / V_V
cj, ɟj, çj, ʝj > c, ɟ, ç, ʝ

Labialization

tw, cw, kw > tʷ, cʷ, p
dw, ɟw, gw > dʷ, ɟʷ, b
fw, θw, sw, çw, xw, hw > ɸ, θʷ, sʷ, çʷ, ʍ, ʍ
vw, ðw, zw, ʝw, ɣw > β, ðʷ, zʷ, ʝʷ, w
nw > ŋʷ
rw > w
lw > ɫ
pw, bw, mw > pp, bb, mm / V_V
pw, bw, mw > p, b, m

Stage 3

Consonants

p         t          c         k
pʲ
            tʷ        cʷ
b          d         ɟ         g
bʲ
             dʷ      ɟʷ
                   ͡tʃ
                   ͡dʒ
ɸ   f  θ  s    ʃ   ç        x         h
      fʲ θʲ 
         θʷ sʷ      çʷ    
β    v ð   z   ʒ   ʝ        ɣ
      vʲ ðʲ
          ðʷ zʷ     ʝʷ
m      n             ɲ      
                                  ŋʷ
w       r             j
          l              ʎ       ɫ
ʍ

Vowels

i        u
    
     a

Tones
High, Low

Syllables

[C]V
Medial consonants may be geminated

Sound changes
Feature spreading

a, u > e, y / _Ci
i, u > e, o / _Ca
i, a > y,o / _Cu

Tone sandhi

Low>  Rising / _High
High>  Falling / High_

Syncope

Primary stress on first syllable, secondary stress on odd syllables

Where 2 identical vowels (modulo tone) occur in adjecent syllables, the vowel in the less stressed syllable is deleted.

Stage 4

Consonants as Stage 3.

Vowels

i y         u
  e       o
       a

Tones
Low, high, rising, falling

Syllables

[C]V[C]

By stage 4, the phonology is more or less where I want it to be, and subsequent stages will mainly be about gramaticalisation and analogy. However, I've left myself some phonological loose ends for later.

The plan is to go backwards and forwards between Stages 0 to 4 for a bit, building up basic vocabulary and grammar, and then move on to the later stages. Going backwards and forwards is partly an attempt to reconcile the diachronic method with my love of hand-crafted vocabulary. The finished product will probably be about Stage 7.