Hit Hotkeys, Easily Fix Subtitles Delay in VLC Media Player

 In this case, what you need is to change the delay time depending on whether the subtitles are before or after the audio. Well, vlc has this great feature that allows user to easily change the subtitle delay by hitting the keyboard shorcuts.
Go to Tools>Preferences on the menu bar. Now the Preferences window opens where you need to enable the Hotkeys on the left bottom corner.

Move the scrollbar to find the "Subtitle delay up" and "Subtitle delay down" on the right hotkey list.  While the video is playing, hit “h” to increase the subtitle delay and “j” to decrease it. The hotkeys could be customized. Double click the row in which the hotkey you want to change, and click the Apply button after you type the new keys. Finally click the Save button.

Each keystroke means a 50 millisecond delay. So if 30s delay is due to applied, you need to hit decent number of times or keep pressing the hotkey untile reach the potint where you want.