Dividend growth model

Hello,
there is a dividend of 0.5 dollars declared. The cum share price is 7.8. Past dividends for 4 years are given.

Please confirm if following treatments are correct:
1) for dividend growth model ex div price is used so 7.8-0.5 considered
2) for the growth I used (0.5/earliest dividend) raised to power 1/4 – 1
3) applied the growth percentage to declared dividend of 0.5. Put the values in the formula for DVM
4) calculated cost of equity.

Awaiting confirmation.
Thanks