Need a little help getting that timeline created? Here's a step-by-step guide to get you on your way:

Step 1:
Gather all the records you have on the family you are creating the timeline for and assemble them by date.

Step 2:
Create an entry for each record, including pertinent information from the record and the source description. (I like to include an abstract, extract, or in some cases a transcription of the record.)

Some typical record entries might look like these:

3 June 1880
1880 US Census, Brooklyn, Kings Co., NY
Kelly, Elizabeth, White, Female, 54, boarder
(Hotel Branting, Madison Ave/58th St.), Single, NY, IRE, IRE
(Source Information: NARA film T9-895, E.D. 584, Page 31, SD 1, 466C. At Ancestry.com: Image 31 of 33. Copy of image at C:\Genealogy\Kelly\Elizabeth\1880 Census.jpeg)

1 April 1883
Kelly, Elizabeth died
(Death notice, and death ctf.)
[Transcriptions edited]

Also, from The Sisters of Charity of New York, 1809-1959, Vol. III by Sister Marie de Lourdes Walsh (New York City: Fordham University Press) Chapter 11, pages 225-226:
". . . Meanwhile the home had been incorporated in 1870 under the legal title of St. Joseph's Home for the Aged, with the following Board of Managers:
Mother Mary Jerome Ely
Sister Mary Regina Lawless
Sister Ann Borromeo Obermeyer
Sister Mary Francis Wallace
Sister Maria Dodge
Sister Francis Borgia Taylor
Miss Elizabeth Kelly
Mrs. Daniel Devlin
. . . Miss Kelly continued on the Board until her death in 1883 . . .")

17 March 1850
Catherine Kelly's death
TOBIN, Catharine; d Mar 17, 1850; bur Mar 19; age 26;
d of consumption; res: 44 N. Water St.
(Website: Known burials at St. Patrick's Cemetery, Rochester, NY, by Richard T. Halsey, August 2001.)

1888-1890
Brooklyn Directory listing
James Kelly, 155 Huntington, Brooklyn, NY, 1889-1890 (Lain's Directory —Ancestry.com database.)

Step 3:
Go back through the records and analyze them, looking for more dates that can be filled in. Some examples:

1814-1815
Kelly, James—born
(Estimated from 1880 U.S. Census data)

6 Jun 1819
Kelly, Jane—born
(Death ctf. 10 January 1882 she was 62 years, 7 months, 4 days)

1821 or before
Kelly, Mary A.—born
(1880 Census—daughter Kate's enumeration lists mother born Ireland)

ca. 1821
Kelly family immigrates from Ireland
(Estimated from birth dates and places of James and Catherine found on U.S. Census entries for James and Catherine's daughter Ann Eliza. Also from James Kelly death certificate in 1896—been in country for 75 years = 1821.)

ca. 1823-4
Kelly, Catherine—born
(Estimated from data on Known burials at St. Patrick's Cemetery, Rochester, NY—See 1850)

1866
James Kelly moves to Brooklyn (per death ctf. in 1896-living in city 30 years)

Because these entries are normally derived from other entries in the same timeline, I don't record the complete source information on each one.

Tips:
I have found that word processing documents allow for the flexibility needed to include as much or as little information needed, and to alleviate the problems that spreadsheets bring in as far as needing different columns, headers, and sizes for different records.

Formatting, sizing, and color-coding can help to make dates stand out, sources easy to pick out, and for delineation between individuals. For example, I usually make the date larger and bolder, have the names bold and color-coded (James uses dark blue print, Catherine—Green, Elizabeth— maroon, etc.), and put sources in italics.

Be sure to include sources. As you add entries, you may run into contradictory information from other sources. Having the sources included allows you to weigh the evidence, and will let you know what records still need to be searched for.

Make a habit of updating your timeline whenever you add new data. They are very useful for planning your next move, and when you decide it's time to write that family narrative, you have the framework already done!

For more on creating timelines, see The Multi-Functional Timeline, by Juliana Smith.