Russell had plenty of warning signs, but he failed to heed them. He knew about the disappointment of the Millerites, and the later Adventists. At first, he did not believe the time proofs for 1873 by Jonas Wendell, the Advent Christian preacher who Russell heard in 1869/1870. Wendell had written a book published in 1870 reapplying some of the Millerite time proofs to the year 1873. (According to his obituary, Wendell had lost his faith for a time after being disappointed when a prediction of Christ's return had failed.) It is likely that Russell heard Wendell personally state these time proofs in sermon or private conversation, or that Russell knew Adventists in the Pittsburgh area that accepted them. Wendell had been the regular preacher to the Advent Christian Church in Pittsburgh around 1869-1871, which would give Russell an opportunity to have become familiar with them. But he rejected them at that time because these timers were expected the burning of the world at the coming of Christ, and Russell had already rejected this idea. Some Adventists had accepted "age-to-come" views, that the earth would survive the coming of Christ, and that the nations under Israel would live on earth during the reign of Christ. It is likely that there were Adventists in the Pittsburgh area that also were age-to-comers and they rejected Wendell's time proofs. In 1871-1873 George Stetson was the regular preacher to the Advent Christian Church there, and Russell, who acknowledged Stetson's influence and preached at his funeral, would have had ample opportunity to have learned from Stetson, and likely attended the services when Stetson preached his sermons. So Russell likely had a continuing presence at the Advent Christian Church for these years. Stetson, taught the corresponding price of the ransom, and wrote articles in the Adventist papers on this, so it is highly likely that Russell gained his understanding from Stetson, and believed that Christ gave up his human nature at death, and became a spirit being at his resurrection, and so would not return as a human being.
In the meantime, the 1873 time movement led by Barbour had failed. Barbour modified his views, taught that Christ had come invisibly in 1874. In 1876, when Russell when had read Barbour's paper, he was influenced to examine the time proofs because Barbour had accepted the "age-to-come" views that there was no burning of the world, and also that of the invisible return, taught Seiss and other prophetic students at that time, which Russell had come to accept. So the earlier objections that Russell had were not present.
If there was one mistake that Russell made, it was accepting these time proofs of Barbour. He knew that Barbour and his followers had been disappointed with their expectations in 1873. Storrs, who had been a mentor to Russell, publicly in his paper disagreed with Barbour and Russell, and was against setting a date for Christ's return. Storrs had been a main proponent for the year 1844 in the Millerite Movement, having been a prominent Millerite preacher, and then publicly renounced it after the disappointment, so Storrs was familiar with the bitter fruit of date-setting.
Russell had set dates for 1874, 1878, 1881, and 1914. There had been an expectation of the rapture/translation/change at each of these dates. In 1881, Russell held that the high calling was closed at that time, basing it up a time parallel with the year 36 A.D. However, after a few years, Russell decided that there was still room in the Little Flock because crowns were being lost. This caused years of confusion among his followers, Bible Students/JWs, as to what class or group they belonged to, and whether were worthy enough to be in the Little Flock, or had been unfaithful and failed and lost their crown, or whether they were spirit-begotten or not.
Russell was willing to make predictions such as 1910 based only on paper measurements of the Great Pyramid, and changed the measurements of the Great Pyramid when his chronology changed.
Russell was aware that the 70 year desolation and the dating of the destruction of Jerusalem in 606/607 B.C. did not agree with the standard dating of 586/587 B.C. and yet continued in his chronology. Today we have more evidence for the 586/587 B.C. dating but even then there was enough evidence.
To set future dates, to publicly preach them, to make the acceptance of them the sickle that separate the wheat from the tares, to tell others to leave their churches because of them, to ask others to sell the books proclaiming them, to encourage Christians to study the books in church instead of the Bible, and then when the dates don't work out, to reexplain them - all of these things have to be seen for what they are - morally and spiritually wrong. It creates unwarranted fears and false hopes, and creates emotional highs and bitter lows of disappointment.
It seems that setting dates is an addiction that resists failure and disappointment. Russell's mistakes have cast a wide shadow on the Bible Students/JWs to this day.