  MeerTime is a five-year Large Survey Project to time pulsars with MeerKAT,
the 64-dish South African precursor to the Square Kilometre Array. The science
goals for the programme include timing millisecond pulsars (MSPs) to high
precision (< 1 $\mu$s) to study the Galactic MSP population and to contribute
to global efforts to detect nanohertz gravitational waves with the
International Pulsar Timing Array (IPTA). In order to plan for the remainder of
the programme and to use the allocated time most efficiently, we have conducted
an initial census with the MeerKAT "L-band" receiver of 189 MSPs visible to
MeerKAT and here present their dispersion measures, polarization profiles,
polarization fractions, rotation measures, flux density measurements, spectral
indices, and timing potential. As all of these observations are taken with the
same instrument (which uses coherent dedispersion, interferometric polarization
calibration techniques, and a uniform flux scale), they present an excellent
resource for population studies. We used wideband pulse portraits as timing
standards for each MSP and demonstrated that the MeerTime Pulsar Timing Array
(MPTA) can already contribute significantly to the IPTA as it currently
achieves better than 1 $\mu$s timing accuracy on 89 MSPs (observed with
fortnightly cadence). By the conclusion of the initial five-year MeerTime
programme in July 2024, the MPTA will be extremely significant in global
efforts to detect the gravitational wave background with a contribution to the
detection statistic comparable to other long-standing timing programmes.
