This is all PTHG says about Joseph's warnings:
It is critical to know when the time period of that “appointment” ended. Latter-day teaching assumes the appointment was kept, and the condition met. The presumption is based on the fact that a small group of saints left behind to complete the work on the temple after the church abandoned the site, dedicated it just before they also abandoned the city.
Two and a half years after the revelation was given, Joseph reminded the saints they needed to complete the Temple. “He said that he could not reveal the fullness of these things until the Temple is completed[.]”
If the saints seemed unmoved by a fading opportunity to receive what was offered to them, Joseph Smith was not. He returned to the issue again early in 1844, this time warning the saints the opportunity might be lost to them:
. . . And I would to God that this temple was now done, that we might go into it, and go to work and improve our time, and make use of the seals while they are on earth.
The Saints have not too much time to save and redeem their dead, and gather together their living relatives, that they may be saved also, before the earth will be smitten, and the consumption decreed falls upon the world.
I would advise all the Saints to go with their might and gather together all their living relatives to this place, that they may be sealed and saved, that they may be prepared against the day that the destroying angel goes forth; and if the whole Church should go to with all their might to save their dead, seal their posterity, and gather their living friends, and spend none of their time in behalf of the world, they would hardly get through before night would come, when no man can work; and my only trouble at the present time is concerning ourselves, that the Saints will be divided, broken up, and scattered, before we get our salvation secure; for there are so many fools in the world for the devil to operate upon, it gives him the advantage oftentimes.” (TPJS, p. 330-331.)
That's not much. One would think that Joseph would give a talk on this every week if the saints were in danger of being rejected over it. But again, I'm not worried about the Nauvoo saints. I'm worried about us. Given the paucity of Joseph's warnings, it is possible that we are also in danger of being rejected and we don't know it.
But why would there be such little warning given the stakes? Let's go back to D&C 124:47:
And it shall come to pass that if you build a house unto my name, and do not do the things that I say, I will not perform the oath which I make unto you, neither fulfil the promises which ye expect at my hands, saith the Lord.If Joseph had threatened the Saints with rejection every week, he possibly could have gotten a temple built before June 1844, but without the saints doing the things God asked, the result still would've been the same.
We might have a similar command hanging over our collective heads, where "if we write a guide and standard, and do not the things that [God] say[s], [God] will not perform the oath which [He] make unto you, neither fulfil the promises which ye expect at [His] hands.
So if we write the best guide and standard ever, but neglect to keep the commandments in the process, either by going beyond Question 2 in the content of the G&S
Second: Do you have faith in these things and receive the scriptures approved by the Lord as a standard to govern you in your daily walk in life, to accept the obligations established by the Book of Mormon as a covenant and to use the scriptures to correct yourselves and to guide your words, thoughts and deeds?or by going beyond Question 4 in the process of creating the G&S
Fourth: And do you covenant to seek to become of one heart with those who seek the Lord to establish His righteousness?---then God may not provide the promises that we expect.