From inception of a monetary economy with a government-issued currency, it is clear that government spending must come before tax payments or purchases of government debt. The order of requirements is basically: (i) government defines its monetary unit of account; (ii) government imposes taxes and other obligations that can only finally be settled in that currency; (iii) government spends (or lends) its currency into existence; (iv) non-government can now obtain the currency and, among other things, pay its taxes and purchase government debt. It is clear that government spending must logically come before tax payments or purchases of government debt because non-government must be able to get hold of the currency before it can do these things
This is an excellent introductory video, scripted and narrated by Geoff Coventry. It is mentioned in the YouTube comments that Stephanie Kelton and others advised on the work. No doubt the video has already appeared on other blogs. The link was provided by acorn in the comments.