Hexagram 16, Yù (Enthusiasm): Line 1
豫卦初六 · 雷地豫 · 中文版
初六：鸣豫，凶。
The line (Legge)
The first SIX, divided, shows its subject proclaiming his pleasure and satisfaction. There will be evil.
Small Image commentary
'The (subject of the) first six proclaims his pleasure and satisfaction:' - there will be evil; his wishes have been satisfied to overflowing.
象曰：初六鸣豫，志穷凶也。
In plain words
Proclaiming one's enjoyment: misfortune. The first line is weak and corresponds to the fourth; carried away by good fortune, it shows off. The Small Image says its aims run out, hence misfortune.
Applying it to your situation
If things are going your way, this line suggests not rushing to broadcast it. What pleasure is better left unspoken?
Position
A broken (yin) line in the first place, which is a yang (odd) place, so it is not in its proper place. Its partner is line 4; one is yin and the other yang, so they respond to each other.
If this line moves
With this line moving alone, Yù changes into Hexagram 51 Zhèn (The Arousing Thunder). The Jiaoshi Yilin verse for this change (Chinese): 焦氏易林·豫之震.
The hexagram
Hexagram 16 Yù (Enthusiasm). The Judgment: Yu indicates that, (in the state which it implies), feudal princes may be set up, and the hosts put in motion, with advantage.
Next: Line 2
English text: James Legge, The Yi King (Sacred Books of the East, vol. 16, 1882), public domain, as transcribed by the Chinese Text Project. Chinese: the received text. Offered for study and reflection, not as prediction. Plain-English readings and position notes by this site.