add first time submission info (#9)

README.md

@@ -22,7 +22,6 @@ Participating teams will be able to submit national- and jurisdiction-specific (
    1. Quantile predictions for epiweekly total laboratory-confirmed COVID-19 hospital admissions. This target is mandatory for any submitted location and forecast horizon.
    2. Individual forecast trajectories for epiweekly total laboratory-confirmed COVID-19 hospitalizations over time (i.e sampled trajectories). This target is optional for any submitted location.
 
-
 Teams are encouraged but not required to submit forecasts for all weekly horizons or for all locations. 
 
 ### Horizons 
@@ -56,6 +55,10 @@ Standard software packages for R and Python can help you convert from dates to e
 
 Detailed guidelines for formatting and submitting forecasts are available in the [`model-output` directory README](model-output/README.md). Detailed guidelines for formatting and submitting model metadata can be found in the [`model-metadata` directory README](model-metadata/README.md).
 
+## Suggested workflow for first time submitters
+First-time pull requests (PRs) into the Hub repository must be reviewed and merged manually; subsequent ones can be merged automatically if they pass appropriate checks. 
+
+ We suggest that teams submitting for the first time make a PR adding their model metadata file to the [`model-metadata` directory](model-metadata) by 4 PM USA Eastern Time on the Wednesday they plan to submit their first forecast. This will allow subsequent PRs that submit forecasts to be merged automatically, provided checks pass.
 
 ## Alignment between CovidHub and FluSight