Benno Jacob (1992, p. 288) explains that in 11:4 Moshe was referring to the upcoming night that tenth plague was going to happen that night. (Hoffmann, 2010, p. 114, mentions this as a possibility.) This understanding of 11:4 means that Moshe told Pharaoh the conversation of 11:4-8 on the morning of the 14th of Nisan since the tenth plague was on the night of the 14th/15th of Nisan, and the Jewish people left Egypt on the 15th of Nisan, Bemidbar 33:3, see also Vayikra 23:5,6. Furthermore, since it is generally assumed that 11:4 is a continuation of the conversation in 10:24-29, this would mean that the entire passage from 10:24-11:8 occurred on the morning of the 14th of Nisan. If this is true, then 10:24-11:8 is not recorded in chronological order since 12:2 records G-d's instructions to Moshe about the tenth plague, at least from the 10th of Nisan and maybe even on the 1st of Nisan, 12:1-20. Moshe relayed this information to the Jewish people no later than the tenth of the month, 12:21-28. With this understanding, the events recorded in 12:1-28, transpired prior to the conversation between Moshe and Pharaoh in 10:24-11:8.
In addition, it could be that the conversation of 10:24-11:8 transpired immediately after the end of the plague of darkness, 10:21-23, which means that the plague of darkness was on the 11th, 12th and 13th of Nisan, as suggested by Benno Jacob (1992, p. 301). This would mean that also 10:21-23, is recorded not in chronological order.
On the other hand, it could be that the conversation between Moshe and Pharaoh recorded in 10:24-11:8 did not occur immediately after the plague of darkness. Instead, following the idea that 12:1-28 occurred before 10:24-11:8, maybe Pharaoh saw the Jewish people had taken their sheep on the tenth of Nisan, and this prompted him to speak to Moshe and Aharon. With this latter possibility, the plague of darkness could have been earlier than the 11th of Nisan, and then only the passage from 10:24-11:8 is recorded out of chronological order.
A possible reason for the Torah recording 10:24 (21?) – 11:8 prior to 12:1-28, even though the conversation recorded in 10:24 (21?) -11:8 occurred afterwards is that had the passage of 10:24 (21?) -11:8 been recorded in its chronological order, then this section would have interrupted between the instructions for the tenth plague, 12:1-28, and the tenth plague, 10:29.
With this understanding, we now know how Moshe told Pharaoh about the tenth plague in 11:4-8. G-d told Moshe about the tenth plague in 12:12,13, and this conversation occurred before the conversation between Moshe and Pharaoh that is recorded in 11:4-8.
In addition, this timing of 10:24 (21?) – 12:28 can explain Moshe’s statement to Pharaoh in 10:29, that they would not see each other again. If the conversation of 10:24-11:8 occurred before 12:1-28, how did Moshe know that he would not see Pharaoh again? The answer is that since the conversation of 10:24-11:8 was on the morning of the 14th of Nisan, Moshe knew that the Jewish people were leaving the next day, so Moshe could tell Pharaoh that they would not see each other again.
Bibliography:
Hoffmann, David (1843-1921), 2010, Commentary on Shemot, translated by Asher Vestreel, Jerusalem: Mossad Harav Kook.
Jacob, Benno (1869-1945), 1992, The second book of the Bible: Exodus, translated with an introduction by Walter Jacob, Hoboken: Ktav Publishing House.