Dedication, how do you understand the following sentence - "While the cloud was passing from the Holiest to the east which took a number of days"?

Matt. 24:27 For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be.

I saw the time of trouble, such as never was,--Jesus told me it was the time of Jacob's trouble, and that we should be delivered out of it by the voice of God. Just before we entered it, (1)we all received the seal of the living God. Then I saw the (2)four Angels cease to hold the four winds. And I saw famine, pestilence and sword, nation rose against nation, and (3)the whole world was in confusion. Then we (4)cried to God for deliverance day and night till we began to hear the bells on Jesus' garment. And I saw Jesus rise up in the Holiest, and as he came out we heard the tinkling of bells, and knew our High Priest was coming out. Then (5)we heard the voice of God which shook the heavens and earth, and gave the 144,000 the day and hour of Jesus' coming. Then the (6)saints were free, united and full of the glory of God, for he had turned their captivity. And I saw (7)a flaming cloud come where Jesus stood and he laid off his priestly garment and put on his kingly robe, took his place on the cloud which carried him to the (8)east where it first appeared to the saints on earth, a small black cloud, which was the sign of the Son of Man. While the cloud was passing from the Holiest to the east which took a number of days, the Synagogue of Satan worshiped at the saints feet. Ellen G. Harmon {DS, March 14, 1846 par. 2}

Then I saw that after Jesus leaves the sanctuary the plagues will be poured out. Said the angel, It is the wrath of God and the Lamb that causes the destruction or death of the wicked. I saw that at the voice of God the saints will be mighty and terrible as an army with banners, but they will not then execute the judgment written. {12MR 248.2}

When Christ shall cease His work as mediator in man's behalf, then this time of trouble will begin. --PP 201 (1890). {LDE 253.1}

When Jesus leaves the most holy His restraining Spirit is withdrawn from rulers and people. --1T 204 (1859). {LDE 255.1}

I saw that the four angels would hold the four winds until Jesus' work was done in the sanctuary, and then will come the seven last plagues. --EW 36 (1851). {LDE 256.2}

When He leaves the sanctuary, darkness covers the inhabitants of the earth. In that fearful time the righteous must live in the sight of a holy God without an intercessor. --GC 613, 614 (1911). {LDE 265.6}

I saw the time of trouble, such as never was,--Jesus told me it was the time of Jacob's trouble, and that we should be delivered out of it by the voice of God. Just before we entered it, (1)we all received the seal of the living God. Then I saw the (2)four Angels cease to hold the four winds. And I saw famine, pestilence and sword, nation rose against nation, and (3)the whole world was in confusion. Then we (4)cried to God for deliverance day and night till we began to hear the bells on Jesus' garment. And I saw Jesus rise up in the Holiest, and as he came out we heard the tinkling of bells, and knew our High Priest was coming out. Then (5)we heard the voice of God which shook the heavens and earth, and gave the 144,000 the day and hour of Jesus' coming. Then the (6)saints were free, united and full of the glory of God, for he had turned their captivity. And I saw (7)a flaming cloud come where Jesus stood and he laid off his priestly garment and put on his kingly robe, took his place on the cloud which carried him to the (8)east where it first appeared to the saints on earth, a small black cloud, which was the sign of the Son of Man. While the cloud was passing from the Holiest to the east which took a number of days, the Synagogue of Satan worshiped at the saints feet. Ellen G. Harmon {DS, March 14, 1846 par. 2}

I suspect she would have referred to a time period encompassing more than three years with an expression like "several years".

“Some of the poor were zealous to attend every conference, taking their whole families with them, consuming a number of days to get to the place of meeting . . . {LS80 264.1}

"While the cloud was passing from the Holiest to the east which took a number of days, the Synagogue of Satan worshiped at the saints feet." What, according to that sentence, was taking place WHILE the cloud was in transit?

It seems clear to me that you intend that when Jesus leaves the sanctuary as mediator and therefore withdraws His restraining Spirit which causes the four winds to blow allowing the plagues to be poured out, He is immediately on his way to earth. Is that supported?

She wrote - "the Synagogue of Satan worshiped at the saints feet." Are we to assume nothing else will happen during that period of time?

Yes. Please see quotes posted above.