When did "to lumber" mean to move clumsily or heavily?

I recently used the word lumber to mean plodding heavily forward, when I wondered how it came to mean that. So, naturally, I Googled it.

A short entry on Etymology Online suggested it came into English around 1300, from the Swedish loma "move slowly, walk heavily".

The OED, though, gives an earlier date:

13(??). E.E. Allit. P. B. 1094: Summe lepre, summe lome, and lomerande blynde.
1530 Palsgr. 586/1, I hoble, or halte, or lomber, as a horse dothe, je cloche.
1697 Dryden Virg. Georg. iii. 229 Let 'em not..lumber o'er the Meads: or cross the Wood.
1728 Pope Dunc. iii. 294 Happier thy fortunes! like a rolling stone, Thy giddy dullness still shall lumber on, Safe in its heaviness shall never stray, But lick up every blockhead in the way.
1771 Foote Maid of B. iii. Wks. (?)
1799 II. 229 Hush! I hear him lumbering in!
1830 Scott Demonol. iii. 100 The massive idol leapt lumbering from the carriage.
1852 Hawthorne Blithedale Rom. I. viii. 138 We..were pretty well agreed as to the inexpediency of lumbering along with the old system any further.
1899 Crockett Kit Kennedy xxii. 153 ‘Ouch..!’ barked Royal lumbering outwards like a great pot-walloping elephant through the shallows.
1902 Blackw. Mag. Mar. 400/1 They lumbered to attention as I entered.

I can see where, by 1899, lumber seems to have today's connotation. But the other entries suggest noise (I hear him lumbering in), or hobbled, or something I don't know at all: The massive idol leapt lumbering from the carriage. (?)

I may have answered my own question here, but is there a clearer point in which "to lumber" entered common English usage, meaning "to move clumsily or heavily"?

Merriam-Webster's Eleventh Collegiate Dictionary (2003) has this entry for lumber in the "move clumsily" sense:

lumber vi {ME lomeren} (14c) 1 : to move ponderously 2 : RUMBLE

The first recorded use of lumber as a noun is from 1552, according to the Eleventh Collegiate:

lumber n {perh. fr. Lombard; fr. the use of of pawnshops as storehouses of disused property} (1552) 1 : surplus or disused articles (as furniture) that are stored away 2 a : timber or logs esp. when dressed for use b : any of various structural materials prepared in a form similar to lumber

The first dictionary occurrences of the verb lumber that I've been able to find are in Samuel Johnson, A Dictionary of the English Language (1756), which offers two:

To LUMBER. v. a. {from the noun.} To heap like useless goods irregularly. Rymer.

To LUMBER. v. n. To move heavily, as burthened with his own bulk. Dryden.

Johnson's entry for the noun lumber is quite brief:

LUMBER. s. {ȝeloma, Saxon, household-stuff} Any thing useless or cumbersome. Grew.

The earliest entry for lumber in any English dictionary that I've checked is from Robert Cawdrey, A Table Alphabeticall (1604):

lumber, old stuffe.

H.C., Gent[leman], The English Dictionarie: or, An Interpreter of Hard English Words, ninth edition (1650), repeats Cawdrey's entry, minus the final e in stuffe.

But the noun lumber is also mentioned in Francis Holyoke, Riders Dictionarie Corrected And Avgmented (1606) as part of an entry for the allied terms "Baggage, trumperie, or lumber."

Johnson's citation of Dryden evidently refers to this instance from Dryden's translation of Virgil's Third Book of the Georgics, reproduced from Annual Miscellany for the Year 1694 (1708), describing cattle:

The Male has done; thy Care must now proceed

To teeming Females; and the promis'd breed.

First let 'em run at large; and never know

The taming Yoak, or draw the crooked Plough.

Let 'em not leap the Ditch, or swim the Flood;

Or lumber o'er the Meads; or cross the Wood:

But range the Forest, by the silver side

Of some cool Stream, where Nature shall provide

Green Grass and fatning Clover for their fare;

And Mossy Caverns for their Noontide lare;

With Rocks above, to shield the sharp Nocturnal air.

Mysteriously, however, this is the only instance I find in Google Books of an instance of lumber used as a verb before 1700, whereas a Google Books search turns up dozens of matches for the noun lumber in the sense of unnecessary accumulated stuff. As a result, I'm left to wonder what became of lumber as a verb between its 14th-century appearance in English as an alteration of the Middle English lomeren (according to the Eleventh Collegiate) and its reappearance in 1696 in Dryden's translation of the Georgics.

The most likely explanation is that some slight difference in spelling of the word is masking early instances of the verb lumber. But a check for lomber (the spelling that Palsgrave used in the 1530 instance cited by the OED as quoted in medica's question) yields no relevant matches, so I remain baffled by the historical gap.

It seems possible that the verb lumber dropped out of general use for a century or more, aside from some limited regional or colloquial use, and that Dryden drew it out of obscurity with his use of it in 1694. In any event, to judge from the Google Books results, lumber as a noun was far more common than lumber as a verb during the seventeenth century and early eighteenth century.

That lomerande (present participle) cited in the OED entry is assumed to be formed from lome a variant of lame.