Reading a chart without a birth time is a skill of subtraction. You keep what the ephemeris gives you and drop what the horizon would have given you, then you build an interpretation that stands on the part you kept. Done properly, the result is a narrower but more honest reading than a full chart built on a guessed time.
The first move is to classify every factor by whether a missing time touches it. This takes five minutes and prevents the single most common failure, which is drifting into house language because it is the habit of reading charts.
Anything anchored to the horizon or the local meridian is out. Anything that is a planet's position on a date is in, with the Moon needing a quick check of the ephemeris for the birth date.
Once sorted, read the confirmed placements first and thoroughly. They hold the bulk of the interpretive weight people expect from a chart anyway.
Sun and Moon are the spine of a reading, and both are usually available. Note whether they are in the same element or different ones, whether they sit in a trine or a square, and what phase that produces. A New Moon birth reads differently from a Full Moon birth, and the phase does not depend on the clock.
Then move to the aspects between the planets. A tight Sun square Saturn or Venus trine Neptune is the same in a timed chart and an untimed one, because both the positions and the angular relationship come from the ephemeris. These hard and soft contacts typically carry more explanatory weight than the houses do anyway.
Check the Moon first, because it is the one sign placement that regularly fails. If the Moon held one sign through your birth date, you have it and you can read it at the sign and even the approximate degree. If it changed sign, you have two candidates and you should say so rather than picking one silently.
The exception worth knowing is the near-midnight case. If the Moon changed sign at 11 PM and you were born in the morning, the earlier sign is close to certain. If it changed at 1 AM and you born at noon, the later sign is close to certain. The ambiguous zone is only as wide as the hours the Moon spent in the two signs that day.
Name the omission out loud. A reader who is told 'these are your sign placements, and here is why houses are not included' understands the reading better than one who is handed a solar chart with no disclaimer. The second person will walk away believing they have a rising sign.
This also protects the reading from the follow-up problem. If you imply you have houses, every subsequent question about career, partnerships, or timing has to be fudged. If you state up front that houses are out of scope, you can answer those questions honestly with 'that needs a birth time, and here is what I can say instead.'
There are three routes from here, and they are worth weighing rather than jumping at. Find the record, which ends the problem and should always come first. Build a clearly labeled workaround chart, either noon-based or solar, if you want to see how the houses would be structured. Or pursue rectification, which infers a time from life events and returns a proposal rather than a fact.
Whichever route you take, keep the uncertainty visible in the output. Mark the difference between a confirmed placement and a proposed one, and if a real birth time surfaces later, expect to revise the reading rather than defending the old version. This is a symbolic tradition refined over centuries of practice, not a validated science, and treating a proposed Ascendant as data would be the least defensible thing a reader can do.