It is a good time to retain a lawyer when you found the target project. The client should communicate with lawyers during negotiation. Sometimes lawyers need to join in the negotiation. The most important thing is that the letter of intent should be signed after it have been reviewed by the lawyer. Some clients start to look for lawyers after the letter of intent has been signed. It may be too late. The letter of intent is the guide of a project. If there is a mistake in the signed letter of intent, it cannot be changed without consent of the other party. Even if the letter of intent is non-banding to both parties, there still is the risk if one party wants to make changes after it has been signed. First of all, the other party may think you are not reliable. Secondly, since you want to change one term, some other terms may be changed as well. If leaving the mistake there, there will be more troubles. The success rate of a project will be significantly decreased if the letter of intent has problems. Therefore, please do retain lawyers before signing the letter of intent.