I would say the most common thought on the matter is that a baby will delay speaking as long as possible, then only when pushed from parents and family, will start to speak. This couldn’t be further from the truth.
In fact, singing will wither away gradually as your baby is able to express themselves clearly with language. My son would use signs often even after speaking the words clearly, however. But he’d almost always say the words along with the sign. Some words, he’d sign and say, while others he would drop the sign and say it instead. Still, other words he’d prefer to sign even after being able to say the words, but only if he couldn’t say them well. In other words, he used signs to clarify and assist him in the most efficient way possible in light of his communication skills and abilities.
By in large, these are the variations your baby will experience too once they’ve been taught to sign. This just goes to reinforce the thought that signing is a tool, and not in any way a means to delay speaking. As soon as your baby is ready to replace a word for a sign, he will. It’s not much more complicated than that!